Write a program to demonstrate all string function.

#include<stdio.h>
#include<conio.h>
#include<string.h>
int main()
{
int i,len;
char s1[25],s2[25];
printf("1. length of string");
printf("\n2. string concat");
printf("\n3. string compare");
printf("\n4. string copy");
printf("\n5. string lower");
printf("\n6. string upper");
printf("\nenter your choice");
scanf("%d",&i);
switch(i)
{
case 1:
printf("\nenter string");
scanf("%s",s1);
len=strlen(s1);
printf("\n the length of string is %d",len);
break;
case 2:
printf("\nenter first string");
scanf("%s",s1);
printf("\nenter second string");
scanf("%s",s2);
strcat(s1,s2);
printf("\nstring after concatination %s",s1);
break;
case 3:
printf("\nenter first string");
scanf("%s",s1);
printf("\nenter second string");
scanf("%s",s2);
i=strcmp(s1,s2);
if(i>0)
printf("first string is greater than second");
else if(i<0)
printf("second string is greate than second");
else
printf("both are same");
break;
case 4:
printf("\nenter first string");
scanf("%s",s1);
printf("\nenter second string");
scanf("%s",s2);
strcpy(s1,s2);
printf("\nstring after concatination %s",s1);
break;
case 5:
printf("\nenter the string");
scanf("%s",s1);
strlwr(s1);
printf("\nstring in lower case is: %s",s1);
break;
case 6:
printf("\nenter the string");
scanf("%s",s1);
strupr(s1);
printf("\nstring in uppser case is: %s",s1);
break;
default:
printf("invalid choice");
break; 
}
}