Commonly Used Functions

The most commonly used functions in the string library ie. Using <string.h> are:

• strcat - concatenate two strings
• strchr - string scanning operation
• strcmp - compare two strings
• strcpy - copy a string
• strlen - get string length
• strncat - concatenate one string with part of another
• strncmp - compare parts of two strings
• strrchr - string scanning operation

strcat:

char *strcat(char *s1, const char *s2);

s1 is a pointer to a string that will be modified. s2 will be copied to the end of s1. s2 is a pointer to a string that will be appended to the end of s1. It returns a pointer to s1 (where the resulting concatenated string resides).

strcpy:

char *strcpy(char *s1, const char *s2);

s1 is a pointer to the destination. s2 will be copied to the end of s1. It returns a pointer to s1 (where the resulting copied string resides).

strlen:

int strlen(char *s1);

s1 is a pointer to the string. It returns the length of the string excluding ‘\0’ character.

Example –

#include <stdio.h>
#include <string.h>

int main(int argc, const char * argv[])
{
/* Define a temporary variable */
char MyString[100];

/* Copy the first string into the variable */
strcpy(MyString, "a4");

/* Concatenate the following two strings to the end of the first one */
strcat(MyString, "academics ");
strcat(MyString, ".com");

/* Display the concatenated strings */
printf("%s\n", MyString);

/* Display the length of the string */
printf(“Length : %d\n”,strlen(MyString));

return 0;
}

Output –
a4academics.com
Length : 15

strchr :

char *strchr(const char *s, int c);

s is a string (terminated by a null character).c is the character to be found. It returns a pointer to the first occurrence of the character c within the string pointed to by s. If c isn't found, it returns a null pointer.

strcmp :

char *strcmp(const char *s1, const char *s2);

s1 and s2 a string (terminated by a null character). It returns the ASCII value difference of the first index of mismatched characters of the given string.

Example -

strcmp(“Samiran”,Saha);

It will return the difference between ASCII value of ‘m’ and ‘a’ ie. 12. Because first mismatch occurs at 3rd index.

strcmp(“Saha”,Saha);

It will return 0 because there is no mismatch in the given string.