C Strings

The string can be defined as the one-dimensional array of characters terminated by a null ('\0'). The character array or the string is used to manipulate text such as words or sentences. Each character in the array occupies one byte of memory, and the last character must always be 0. The termination character ('\0') is important in a string since it is the only way to identify where the string ends. When we define a string as char s[10], the character s[10] is implicitly initialized with the null in the memory.

There are two ways to declare a string in c language.

  1. By char array
  2. By string literal

Let's see the example of declaring string by char array in C language.

  1. char ch[10]={'j', 'a', 'v', 'a', 't', 'p', 'o', 'i', 'n', 't', '\0'};  

As we know, array index starts from 0, so it will be represented as in the figure given below.

C Strings

While declaring string, size is not mandatory. So we can write the above code as given below:

  1. char ch[]={'j', 'a', 'v', 'a', 't', 'p', 'o', 'i', 'n', 't', '\0'};  

We can also define the string by the string literal in C language. For example:

  1. char ch[]="javatpoint";  

In such case, '\0' will be appended at the end of the string by the compiler.

String Example in C

Let's see a simple example where a string is declared and being printed. The '%s' is used as a format specifier for the string in c language.

  1. #include<stdio.h>  
  2. #include <string.h>    
  3. int main(){    
  4.   char ch[11]={'j', 'a', 'v', 'a', 't', 'p', 'o', 'i', 'n', 't', '\0'};    
  5.    char ch2[11]="javatpoint";    
  6.     
  7.    printf("Char Array Value is: %s\n", ch);    
  8.    printf("String Literal Value is: %s\n", ch2);    
  9.  return 0;    
  10. }    

Output

Char Array Value is: javatpoint
String Literal Value is: javatpoint

Using the length of string

Let's see an example of counting the number of vowels in a string.

  1. #include<stdio.h>  
  2. void main ()  
  3. {  
  4.     char s[11] = "javatpoint";  
  5.     int i = 0;   
  6.     int count = 0;  
  7.     while(i<11)  
  8.     {  
  9.         if(s[i]=='a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'u' || s[i] == 'o')  
  10.         {  
  11.             count ++;  
  12.         }  
  13.         i++;  
  14.     }  
  15.     printf("The number of vowels %d",count);  
  16. }  

Output

The number of vowels 4