The famous book The C Programming Language was written by Kernighan and. Ritchie in .. There are quite a number of format specifiers for printf. Here are. The first chapter deals with the fundamental concepts of C language. The second . The formatted input/output functions read and write all types of values. Input. C Programming Notes. Introductory C Programming Class Notes, Chapter 1. Steve Summit. These notes are part of the UW Experimental College course on.
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C is a programming language developed at AT & T's Bell Laboratories of USA . The final linked file, which is in an executable object code format, is stored in .. Notes: Do while loop used rarely when we want to execute a loop at least once. C is a general-purpose, procedural, imperative computer programming enough understanding on C programming language from where you can take yourself. C Programming lesforgesdessalles.info - Download as PDF File .pdf), Text File .txt) or read function which will format and print output on the terminal (unless some other.
You could declare a structure student as: A negative constant is preceded by a minus sign. C data types are defined as the data storage format that a variable can store a data to perform a specific operation. There is no limit for the input string. Here is the list of keywords used in Standard C; you will notice that none of them use upper-case letters.
Structure of a C program is defined by a set of rules called protocol, to be followed by programmer while writing a C program… more…. C data types are defined as the data storage format that a variable can store a data to perform a specific operation.
Data types are used to define a variable before using in a program. Size of variable, const and array are determined by data types. There are four data types in the C language. They are…. C tokens, Identifiers and Keywords are the basics in a C program.
All are explained in this page with definition and simple example programs. C tokens are the basic building blocks in C language which are constructed together to write a C program. Each program element in a C program is given a name called identifiers…. C Constants are also like normal variables. Constants refer to fixed values. They are also called as literals. Constants may be belonging to any of the data type…. C variable is a named location in a memory where a program can manipulate the data.
This location is used to hold the value of the variable. The value of the C variable may get changed in the program. The C variable might be belonging to any of the data types like int, float, char etc…. The symbols which are used to perform logical and mathematical operations in a C program are called C operators. These C operators join individual constants and variables to form expressions. Operators, functions, constants and variables are combined together to form expressions….
In decision control statements C — if else and nested if , group of statement is executed when the condition is true. If the condition is false, then, else part statements are executed. In C programming, there are 3 types of decision making control statements in C language. Loop control statements in C programming are used to perform looping operations until the given condition is true.
Control comes out of the loop statements once the condition becomes false. There are 3 types of loop control statements in C language. The statements which are used to execute only specific block of statements in a series of blocks are called case control statements. There are 4 types of case control statements in C programming. Integer Constant: A constant number without a decimal point is an integer constant. The following are examples of invalid numeric constant.
The reason why each is invalid is also given. C allows a number to be written in three different number systems. This is the base 10 number system. This system uses the digits from 0 to 9. This is the base 8 number system. This system uses the digits 0 to 7. The first digit must be zero 0 in order to identify it as an octal number. Following are examples of valid octal integer constants. This is the base 16 number system. The letters A through F represent the decimal quantities 10 through 15 respectively.
A hexadecimal integer constant must begin with a 0x or 0X. It can then be followed by sequence of valid digits. Following are examples of valid hexadecimal integer constants. Floating Point Constant: A constant number with decimal is a floating point number.
Such numbers may also be expressed in exponential scientific form. For example the value The mantissa must be real or integer. The exponent must be an integer a minus or optional plus sign. Following are examples of valid floating point constants. Character Constant: Character constant is a single character enclosed in apostrophes i.
The following are examples of valid character constants. In above the last constant has a blank space enclosed in apostrophes. String Constant: String constant is a combination of valid character enclosed with quotation marks i. The following are examples of valid string constants.
Test Yourself: Identify the following as valid or invalid octal integer constants? Which of the following are invalid hexadecimal integer constants? Why are the following numbers invalid floating point constants? Variable Declaration In general a C program will make use of variables to store data. All variables used in a program must be declared with specific data type. The syntax to declare a variable is: The variables are separated by comma. A declaration statement must end with a semicolon The following lines declares four variables: Assignment A variable can be assigned value after declaration.
The example shows three variables declared of type integer. The variables are assigned values later in the lines that follow.
In these lines: For multiple assignments the following syntax is used: Arithmetic Expressions In C, arithmetic expression is a combination of constants, variables and operators arranged as per the syntax of the language. Some examples of algebraic expression and C expression is given below: Evaluation of Arithmetic Expressions: The basic evaluation procedure is from the left to the right.
An arithmetic expression within parentheses is evaluated left-to-right using the rules of precedence of operators.
There are two priority levels for arithmetic operators in C. High priority: The evaluation is done in two left-to-right passes. During the first pass the high priority operators are applied.
During the second pass the low priority operators are applied. Consider the expression: The expression for given values is: First Pass Second Pass: The order of evaluation can be changed by using parenthesis. When an expression is written in parenthesis it gets highest priority.
For example, in the expression: When parentheses are nested, the innermost parentheses have highest priority. For example: Parentheses can also be used to improve the readability of the program. Expressions Expression is a single value or a combination of values and variables which are connected by operators. A static variable can be initialized by using keyword static before variable name.
A static local variable is different from local variable. It is initialized only once no matter how many times that function in which it resides is called. It may beused as a count variable. Bhushan Vardhekar bvardhekar gmail. Value of count1 is 1, Value of count2 is 1 Value of count1 is 2, Value of count2 is 1 Value of count1 is 3, Value of count2 is 1 3.
What is a register variable? Register variables are stored in the CPU registers. Its default value is a garbage value. Scope of a register variable is local to the block in which it is defined. Lifetime is till control remains within the block in which the register variable is defined.
Variable stored in a CPU register can always be accessed faster than the one that is stored in memory. Therefore, if a variable is used at many places in a program, it is better to declare its storage class as register Example: Note that register keyword may be ignored by some compilers. Where is an auto variables stored? Main memory and CPU registers are the two memory locations where auto variables are stored. Auto variables are defined under automatic storage class.
They are stored in main memory. Memory is allocated to an automatic variable when the block which contains it is called and it is de-allocated at the completion of its block execution.
Auto variables: Default value: Extern variables: The scope of theextern variables is Global. The file f2. The compiler should know the datatype of x and this is done by extern definition.
Global variables: These variables are accessible throughout the program. They can be accessed by all the functions in the program. Their default value is zero. Register variables: The scope of the register variables is local to the block in which the variables are defined. The variables which are used for more number of times in a program are declared as register variables for faster access.
Memory is allocated at the beginning of the program execution and it is reallocated only after the program terminates. The scope of the static variables is local to the block in which the variables are defined.
Every time this function is called, 'a' does not get initialized. Local variables: They can be accessed only by function or block in which they are declared. Their default value is a garbage value. Prepared by: What are storage memory, default value, scope and life of Automatic and Register storage class? Automatic storage class: Register storage class: CPU registers. What are storage memory, default value, scope and life of Static and External storage class?
Static storage class: External storage class: What is the difference between 'break' and 'continue' statements? What is the difference between 'for' and 'while' loops? The loop repeats for 5 times and prints value of 'i' each time.
In while loop statement, only condition statement is present. Element found at 5th location Explanation: Here flag is initialized to zero. If found, value of flag is set to 1 and 'while' loop terminates.
Bitwise AND operator. Suppose in byte that has a value Since we want to check the bit number 3, the second operand for AND operation we choose is binary , which is equal to 8 in decimal. ANDing operation: The result turned out to be a 8 since the third bit of operand was ON. Had it been OFF, the bit number 3 in the resulting bit pattern would have evaluated to 0 and complete bit pattern would have been Thus depending upon the bit number to be checked in the first operand we decide the second operand, and on ANDing these two operands the result decides whether the bit was ON or OFF.
Which bitwise operator is suitable for turning OFF a particular bit in a number? What is equivalent of multiplying an unsigned int by 2: Left shifting of an unsigned integer is equivalent to multiplying an unsigned int by 2. Program to illustrate left shift and right shift operations. Left shift by 1 position multiplies a number by two. Right shift divides a number by 2. What is an Enumeration Constant? Enumeration is a data type.
We can create our own data type and define values that the variable can take. This can help in making program more readable. It can have two possible values - on or off. We can give values to these variables: What is a structure?
A structure is a collection of pre-defined data types to create a user-defined data type. Let us say we need to create records of students. Each student has three fields: You could declare a structure student as: Now these objects and their fields could be accessed by saying student1. What are the advantages of unions? Union is a collection of data items of different data types. It can hold data of only one member at a time though it has members of different data types.
If a union has two members of different data types, they are allocated the same memory. The memory allocated is equal to maximum size of the members. The data is interpreted in bytes depending on which member is being accessed. Out of these two variables, 'point' is larger variable which is of float data type and it would need 4 bytes of memory. Therefore 4 bytes space is allocated for both the variables.
Both the variables have the same memory location. They are accessed according to their type. Union is efficient when members of it are not required to be accessed at the same time. What are the differences between a structure and a union? Structures and Unions are used to store members of different data types. In this case, float is the largest-sized data type. Hence memory allocated to this union is 4 bytes. How can typedef be to define a type of structure?
Its purpose is to redefine the name of an existing variable type. It provides a short and meaningful way to call a data type. Use of typedef can reduce length and complexity of data types.
Usually uppercase letters are used to make it clear that we are dealing with our own data type. Write a program that returns 3 numbers from a function using a structure. A function in C can return only one value. If we want the function to return multiple values, we need to create a structure variable, which has three integer members and return this structure.
In this program, we use C structure to return multiple values from a function. Here we have a structure holding three int variables and a function which returns it. In this program, 'accept3val' is a structure used to accept the values returned by the function. It accepts those values and shows the output. In code snippet below: Arguments to the function must be pointers to the structure, Date and integer variables date, month, year. Date is a structure with three int variables as members.
Program to illustrate a function that assigns value to the structure. Two variables of type Date are created and named 'date1', 'date2'. What are header files?
Are functions declared or defined in header files? Functions and macros are declared in header files. Header files would be included in source files by the compiler at the time of compilation. Header files are included in source code using include directive. A header file may contain declarations of sub-routines, functions, macros and also variables which we may wantto use in our program.
Header files help in reduction of repetitive code. Syntax of include directive: But it is recommended only to declare functions and not to define in the header files. When we include a header file in our program we actually are including all the functions, macros and variables declared in it.
In case of pre-defined C standard library header files ex stdio. Code for C standard functions are linked and then the program is executed. Header files with custom names can also be created. What are the differences between formal arguments and actual arguments of a function?
An argument is an expression which is passed to a function by its caller or macro by its invoker in order for the function or macro to perform its task. It is an expression in the comma-separated list bound by the parentheses in a function call expression. Actual arguments: The arguments that are passed in a function call are called actual arguments.
These arguments are defined in the calling function. Formal arguments: The scope of formal arguments is local to the function definition in which they are used. Formal arguments belong to the called function. Formal arguments are a copy of the actual arguments. A change in formal arguments would not be reflected in the actual arguments.
What is pass by reference in functions?
Pass by Reference: In this method, the addresses of actual arguments in the calling function are copied into formal arguments of the called function. This means that using these addresses, we would have an access to the actual arguments and hence we would be able to manipulate them. C does not support Call by reference. But it can be simulated using pointers.
In the main function, address of variables m, n are sent as arguments to the function 'swap'. As swap function has the access to address of the arguments, manipulation of passed arguments inside swap function would be directly reflected in the values of m, n. What is pass by value in functions? Pass by Value: In this method, the value of each of the actual arguments in the calling function is copied into corresponding formal arguments of the called function. In pass by value, the changes made to formal arguments in the called function have no effect on the values of actual arguments in the calling function.
In the main function, value of variables m, n are not changed though they are passed to function 'swap'. Swap function has a copy of m, n and hence it can not manipulate the actual value of arguments passed to it. Out of the functions fgets and gets , which one is safer to use and why? Out of functions fgets and gets , fgets is safer to use. There is no limit for the input string.
The string can be too long and may lead to buffer overflow. The function fgets takes three arguments. First argument: Second argument: Third argument: Thereby it avoids overflow of input buffer. Thus fgets is preferable to gets. What are the differences between getchar and scanf functions for reading strings? Differences between getchar and scanf functions for reading strings: What is the difference between the functions strdup and strcpy?
In strcpy function both source and destination strings are passed as arguments. User should make sure that destination has enough space to accommodate the string to be copied. If successful, strcpy subroutine returns the address of the copied string.
Otherwise, a null pointer is returned. Example Program: This is because string 'myname' is declared to be of size 10 characters only. In the above program, string "nodalo" is copied in myname and is printed on output screen. Function will copy the contents of string to certain memory location and returns the address to that location.
Function returns address of the memory location where the string has been copied. In case free space could not be created then it returns a null pointer. Program to illustrate strdup. String myname consists of "interviewmantra.
Contents of myname are copied in a memory address and memory is assigned to name. At the end of the program, memory can be freed using free name ; What is a pointer in C? A pointer is a special variable in C language meant just to store address of any other variable or function.
It follows a special arithmetic called as pointer arithmetic. A pointer is declared as: A pointer to an integer with name ap was declared.
The pointer ap is now said to point to a. This operator gives the value at the address pointed by the pointer. That is because ap points to a. Pointer arithmetic is different from ordinary arithmetic. Here ap is pointing to an integer variable hence ap is incremented by 2 or 4 bytes depending upon the compiler.
What are the advantages of using pointers? Pointers are special variables which store address of some other variables. Pointers allow us to pass values to functions using call by reference. This is useful when large sized arrays are passed as arguments to functions. A function can return more than one value by using call by reference. Dynamic allocation of memory is possible with the help of pointers. We can resize data structures.
For instance, if an array's memory is fixed, it cannot be resized. But in case of an array whose memory is created out of malloc can be resized. Pointers point to physical memory and allow quicker access to data. What is the equivalent pointer expression for referring an element a[i][j][k][l], in a four dimensional array? Consider a multidimensional array a[w][x][y][z]. Example program to illustrate pointer denotation of multi-dimensional arrays.
This output may differ from computer to computer as the address locations are not same for every computer.