Develop a C program to demonstrate the use of strcat(), strlwr(), and strupr() functions

Develop a C program to demonstrate the use of strcat(), strlwr(), and strupr() functions.

Code

#include <stdio.h>
#include <string.h>
int main() {
   char str1[100] = "This is ", str2[] = "practicalserver.net", str3[] = "PRACTICALSERVER";
   // concatenates str1 and str2
   // the resultant string is stored in str1.
   puts(strcat(str1, str2));
   // converting the given string into lowercase.
   puts(strlwr(str3));
   // converting the given string into uppercase.
   puts(strlwr(str2));
   return 0;
}

Output

You are a programmer, guess the output it's simple...