What is a string in C | String Methods with Examples

 Strings in C:

 String: In C, a string is a sequence of characters. A string is terminated by the null character called null( \0 ) [null means nothing, it holds zero]. The null(termination) character is important in a string it is the only way to identify where the string ends. When you define a string, you must reserve a space for the null(\0)  character.

    For example, to declare a string with the size that holds n characters, the size of the array must be at least n+1. This is because the last index is implicitly initialized with the null in memory.

There are two ways to declare a string in C:

1. By character array

2. By string literal

By character array: Strings are actually a one-dimensional array of characters terminated by the null character '\0'. 

Declaring string by character array in C:

    char str[10] = {'L','e','a','r','n','c','o','d','e'}; 

    The size of the character array must be the (length of the string)+1.

    when declaration and initialization are done simultaneously, size is not mandatory. so we can write the above code as

    char str[] = {'L','e','a','r','n','c','o','d','e'}; 

By string literal: The array initialization takes place in a string literal. Actually, you don't need to place the null character at the end of a string constant. The C compiler automatically places the '\0' at the end of the string literal.

Declaring string by using the string literal in C:

    char str[ ] = "Learncode";

    The compiler automatically creates an array of 10 characters that is sufficient enough to hold the Learncode text and \0.

Example1: C program to declare and print a string without for loop.

   Program

    Output:

   Explanation: The '%s' is used as a format specifier for input and output of string in C language. More about Format specifiers. 

Example2: C program to print the string using for loop.

   Program:

    Output:

 

    Explanation: The '%c' is used as a format specifier for printing each character in the string. Variable i is used as indexing in the string.

Example3: C program to take a string as input and print the string.  

   Program: 

    Output:

    String Methods: If we want to use string methods, we need to include "string.h" header file.

    1. strlen(string_name) : Returns the length of the string.

    2. strcpy(destination, source) : Copy the source string to destination string.

    3. strcat(first_string, second_string) : Joins the first string with the second string and stored the result in first string.

    4. strcmp(first_str, second_str) : Returns 0 if s1 and s2 are same, less than 0 if s1<s2, greater than 0 if s1>s2.

    5. strrev(string) : Returns  reverse sting.

    6. strlwr(string) : Returns string characters in lower case.

    

    7. strupr(string) :  Returns string characters in lower case.

    Example: Implement a C program for string methods.

   Program:

    

   Output:

   

   

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