C String Functions

C String Functions

All String standard library functions can be used by including string header file 'string.h' in any C program.

strlen - used to find the number of characters in the string.

strcpy - used to copy the string to another string variable.

strcat - used to concatenates the strings.

strcmp - used to compare two strings.

C Program to Find String Length

Prints the number of characters in the string.

#include<stdio.h>                                                             
#include<string.h>                                                         
                                                                                
void main()                                                                     
{                                                                               
    char str1[] = "codingpointer.com";                                          
                                                                                
    int len = strlen(str1);                                                     
                                                                                
    printf("String '%s' length: %d", str1, len);                                
                                                                                
}  

Output:

$ cc strlen.c
$ ./a.out 
String 'codingpointer.com' length: 17

C Program to Copy String to another String Variable

Copy's the string into another string variable.

strcpy(str2, str1)

here copy's the string 1 into string variable 'str2'.

#include<stdio.h>                                                             
#include<string.h>                                                         
 
void main()                                                                     
{                                                                               
    char str1[] = "codingpointer.com";                                          
    char str2[20];                                                              
                                                                                
    strcpy(str2, str1);                                                         
    printf("String Copy: %s", str2);                                            
                                                                                
} 

Output:

$ cc strcpy.c 
$ ./a.out 
String Copy: codingpointer.com

C Program to Concatenate two strings

concatenates string in str2 with string in str1.

strcat(str1, str2)

strcat Example:

#include<stdio.h>                                                             
#include<string.h>                                                         
                                                                                
void main()                                                                     
{                                                                               
    char str1[] = "codingpointer";                                              
    char str2[] = ".com";                                                       
                                                                                
    strcat(str1, str2);                                                         
    printf("String concatenation: %s", str1);                                   
                                                                                
}   

Output:

$ cc strcat.c 
$ ./a.out 
String concatenation: codingpointer.com[

C Program to Compare Strings

int result = strcmp(string1, string2);

str1 is greater than str2 if result is greater than or equal to 1.

str1 is less than str2 if result is less than or equal to -1.

str1 and str2 are same if result is zero.

#include<stdio.h>                                                             
#include<string.h>                                                                
                                                                                
void main()                                                                     
{                                                                               
    char str1[] = "codingpointer";                                              
    char str2[] = ".com";                                                       
    int cmp;                                                                    
    cmp = strcmp(str1, str2);                                                   
    printf("String comparison '%s' and '%s': %d\n", str1, str2, cmp);           
                                                                                
    cmp = strcmp(str1, str1);                                                   
    printf("String comparison '%s' and '%s': %d\n", str1, str1, cmp);           
                                                                                
    cmp = strcmp(str2, str1);                                                   
    printf("String comparison '%s' and '%s': %d\n", str2, str1, cmp);           
}  

Output:

$ cc strcmp.c 
$ ./a.out 
String comparison 'codingpointer' and '.com': 53
String comparison 'codingpointer' and 'codingpointer': 0
String comparison '.com' and 'codingpointer': -53