Using - C
  
 Source Code
  

    
#include<stdio.h>
#include<ctype.h>
     
void main() {
  char str[1024];
  int i;
  printf("Enter the String:  ");
  gets(str);

for(i=0; str[i] != '\0'; i++) {
  str[i] = toupper(str[i]);
}

printf("%s",str);
}
    

Enter the String:  welcome
WELCOME

        
Using - C++
        
 Source Code
        

        
#include<iostream>
#include<ctype.h>
using namespace std;

int main() {
  string str;
  cout<< "Enter the String:  ";
  getline(cin,str);

for(int i=0; str[i] != '\0'; i++) {
  str[i] = toupper(str[i]);
}

cout<< str;
return 0;
}
      

Enter the String:  how are you ?
HOW ARE YOU ?