Program to illustrate string functions

String functions : 

string functions used in c are
1.string length  ----- strlen()
2.string copy    -----  strcpy()
3.string reverse ----- strrev()
4.string compare  -----  strcmp()
5.string concatenate  -----  strcat()
6.string upper  -----  strupr()
7.string lower  -----  strlwr()

Program 1: string length  ----- strlen()

// program to illustrate string length ----strlen
#include<stdio.h>
#include<string.h>
#define pf printf
#define sf scanf
void main()
 {
    char name[20];   
    int l;
    pf("\nenter any string :  ");
    sf("%[^\n]s",name);
    l=strlen(name);
    pf("\nentered name is : %s and its length is : %d",name,l);
}

output:

Program 2: string copy  ----- strcpy()

// program to illustrate string copy ----strcpy
#include<stdio.h>
#include<string.h>
#define pf printf
#define sf scanf
void main()
 {
    char name1[20],name2[44];   
    pf("\nenter any string in name1 :  ");
    sf("%[^\n]s",name1);
    strcpy(name2,name1);
    pf("\ncopied string in name2 is : %s",name2);
}
output:

Program 3: string reverse  ----- strrev()
  
    // program to illustrate string reverse using strlen()
    #include <stdio.h>
    #include <string.h>
    int main()
    {
      int i=0, j, temp;
      char s[22];
      printf("\n\n Enter any string :");
      scanf("%s", s);
      j=strlen(s) - 1;
      printf("\n\n Entered string is : %s and its length is %d", s,j+1);
      while(i < j)
      {
        temp = s[i];
        s[i++] = s[j];
        s[j--] = temp;
      }
      printf("\n\n Reverse string is: %s", s);
    }

output:

Program 4: string compare  ----- strcmp()

// program to illustrate string compare ----strcmp
#include<stdio.h>
#include<string.h>
#define pf printf
#define sf scanf
void main()
 {
    char name1[20],name2[44];
    int r;    
    pf("\nenter any string in name1 :  ");
    sf("%[^\n]s",name1);
    pf("\nenter any string in name2 :  ");
    sf("%s",name2);
    r=strcmp(name1,name2);
    if (r == 0)  
        pf("\nBoth the strings are equal");
    else
        pf("\nBoth the strings are not equal");
}

output:

Program 5: string concatenate  ----- strcat()

// program to illustrate string concatenate ----strcat
#include<stdio.h>
#include<string.h>
#define pf printf
#define sf scanf
void main()
 {
    char name1[20],name2[44];
    int r;    
    pf("\nenter any string in name1 :  ");
    sf("%[^\n]s",name1);
    pf("\nenter any string in name2 :  ");
    sf("%s",name2);
    strcat(name1,name2);
    pf("\nconcatenated string is : %s",name1);
 }

output:

Program 6: string upper  ----- strupr()

// program to illustrate string upper ----strupr using functions
#include<stdio.h>
#include<string.h>
#include<ctype.h>
void strupper ( char* );
void main()
 {
  char string[] = {"r k raju"};
  printf( "%s\n", string );
  strupper( string );
  printf( "%s\n", string );
 }

void strupper ( char *p )
{
  while( *p )
  {
   *p=toupper( *p );
   p++;
  }
}

output:

Program 7: string lower  ----- strlwr()

// program to illustrate string upper ----strupr using functions
#include<stdio.h>
#include<string.h>
#include<ctype.h>
void strupper ( char* );
void main()
 {
  char string[] = {"r k raju"};
  printf( "%s\n", string );
  strupper( string );
  printf( "%s\n", string );
 }

void strupper ( char *p )
{
  while( *p )
  {
   *p=tolower( *p );
   p++;
  }
}


output: