Built-in String Functions in C

In C there are 6 types of library functions as mentioned below.

String functions

1. strcpy(s1,s2);        //Copies one string(s1) into another string(s1).
2. strcat(s1,s2);        //Concatenates two strings.
3. strlen(s1);             //Returns the length of string.
4. strcmp(s1,s2);     //Compare two strings.
5. strchr(s1,ch);
6. strstr(s1,s2);

Below program compares 2 strings

#include<stdio.h>              

#include<string.h>

void main()

{

    char str1[15],str2[15];

    printf("Enter the first string\n");

    gets(str1);

    printf("Enter the second string\n");

    gets(str2);

    if( strcmp(str1,str2) == 0 )

     {

      printf("String is equal.\n");

     }

    else if( strcmp(str1,str2)< 0)

     {

      printf("Str1 is less than str2\n");

     }

    else

     {

      printf("Str1 is greater than str2\n");

     }

    getchar();

}

Below program concatenates 2 strings.

#include<stdio.h>             

#include<string.h>

void main()

{

   char str1[10];

   char str2[10];

      //accept the first string

     printf("Enter First string");

     scanf("%s",str1);

           

       //accept the second string

     printf("Enter second string");

     scanf("%s",str2);

           

      //concatenate string2 into string1

     strcat( str1, str2);

           

     printf("Concatenated string is: %s\n", str1 );

 getchar();

}

Below program will illustrate how we can format the string using printf function.

#include<stdio.h>

void main()

{

   //print whole string

  printf("*%s*\n", "Sagar Salunke");

     

    //Reserve 50 spaces for printing string...

      //if string is less than 50, oher characters will be blank spaces

      //- sign indicates that printing will be left justified

   printf("*%-50s*\n", "Sagar Salunke");

      //Reserve 50 spaces for printing string...

      //if string is less than 50, oher characters will be blank spaces

      //No sign indicates that printing will be right justified

    printf("*%50s*\n", "Sagar Salunke");

     //print 5 characters from string...

    printf("*%.5s*\n", "Sagar Salunke");

      //print 10 characters from string...

    printf("*%.10s*\n","Sagar Salunke");

      //Reserve 50 spaces for printing string...

      //but print only 10 characters from string...

  printf("*%50.10s*\n","Sagar Salunke");

      //Reserve 50 spaces for printing string...

      //but print only 10 characters from string right justified...

    printf("*%-50.10s*\n","Sagar Salunke");

 getchar();

}

Below program will append one string to another.

#include<stdio.h>

#include<string.h>

void main()

{

char str1[100];

char str2[20];

char str3[30];

int i=0,str1len,str2len;

printf("\nEnter first string -> ");

scanf("%s",str1);

printf("\nEnter second string -> ");

scanf("%s",str2);

//using built in function from string.h library

printf("\n Concatenated string is %s",strcat(str1,str2));

//using user defined logic.

//1. find the length of the both strings and then use for loop.

str1len = strlen(str1);

str2len = strlen(str2);

while(i < str2len)

{

str1[str1len+i] = str2[i];

i++;

}

str1[str1len+i] = '\0';

printf("\nWithout using strcat -> %s", str1 );

getchar();

}

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