What is C language
C is a computer programming language. That means that you can use C to create lists of instructions for a computer to follow. C is one of thousands of programming languages currently in use .C is a high-level and general purpose programming language that is ideal for developing firmware or portable applications. Originally intended for writing system software, C was developed at Bell Labs by Dennis Ritchie for the Unix Operating System (OS) in the early 1970s.
Control Statement
C is a computer programming language. That means that you can use C to create lists of instructions for a computer to follow. C is one of thousands of programming languages currently in use. Arithmetic operator are used for mathematical calculationthese operator are binary operator that work with integerfloating point number and every character. :Arithmetical operator are: Operator Meaning + Addition - Subtraction * Multiplication / Division % Module division. Relational operator are used to compare two operands.Operands may be variable, constant or expression. Operator Meaning < Is less than <= Is less than equal to > Is greater than >= Is greater than equal to == Equal to != is not equal to main(){ int a=10,b=20,c=30,d,e; d=a>b; e=b<=c; printf(“%d %d”,d,e); getch();} Output:- 01 Are used to combine (compare) two or more condition.Logical Operator are:- Operator Meaning && Logical AND || Logical OR ! Logical NOT.
Functions
A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. You can divide up your code into separate functions.You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division is such that each function performs a specific task.A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.The C standard library provides numerous built-in functions that your program can call. For example, strcat() to concatenate two strings, memcpy() to copy one memory location to another location, and many more functions.A function can also be referred as a method or a sub-routine or a procedure, etc.
Array
Arrays a kind of data structure that can store a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.Instead of declaring individual variables, such as number0, number1, ..., and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and ..., numbers[99] to represent individual variables. A specific element in an array is accessed by an index. All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element. Arrays in C Declaring Arrays To declare an array in C, a programmer specifies the type of the elements and the number of elements required by an array as follows − type arrayName [ arraySize ]; This is called a single-dimensional array. The arraySize must be an integer constant greater than zero and type can be any valid C data type. For example, to declare a 10-element array called balance of type double, use this statement
Pointer
Pointers in C are easy and fun to learn. Some C programming tasks are performed more easily with pointers, and other tasks, such as dynamic memory allocation, cannot be performed without using pointers. So it becomes necessary to learn pointers to become a perfect C programmer. Let's start learning them in simple and easy steps.A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, you must declare a pointer before using it to store any variable address. The general form of a pointer variable declaration is − type *var-name; Here, type is the pointer's base type; it must be a valid C data type and var-name is the name of the pointer variable. The asterisk * used to declare a pointer is the same asterisk used for multiplication. However, in this statement the asterisk is being used to designate a variable as a pointer. Take a look at some of the valid pointer declarations
String
Strings are actually one-dimensional array of characters terminated by a null character '\0'. Thus a null-terminated string contains the characters that comprise the string followed by a null.The following declaration and initialization create a string consisting of the word "Hello". To hold the null character at the end of the array, the size of the character array containing the string is one more than the number of characters in the word "Hello."
Structure And Union
Arrays allow to define type of variables that can hold several data items of the same kind. Similarly structure is another user defined data type available in C that allows to combine data items of different kinds. Structure in c language is a user defined datatype that allows you to hold different type of elements.Each element of a structure is called a member. It works like a template in C++ and class in Java. You can have different type of elements in it.It is widely used to store student information, employee information, product information, book information etc.
File Handling
File Handling in c language is used to open, read, write, search or close file. It is used for permanent storage. A file represents a sequence of bytes, regardless of it being a text file or a binary file. C programming language provides access on high level functions as well as low level (OS level) calls to handle file on your storage devices. This chapter will take you through the important calls for file management.
Preprocessor
The C Preprocessor is not a part of the compiler, but is a separate step in the compilation process. In simple terms, a C Preprocessor is just a text substitution tool and it instructs the compiler to do required pre-processing before the actual compilation. We'll refer to the C Preprocessor as CPP.
All preprocessor commands begin with a hash symbol (#). It must be the first nonblank character, and for readability, a preprocessor directive should begin in the first column. The following section lists down all the important preprocessor directives −