Enter a string, change all lowercase letters in the string to uppercase letters, the size of the array does not exceed 30

Enter a string, change all lowercase letters in the string to uppercase letters, and the size of the array does not exceed 30.

Input example:
A set of inputs is given here. For example:

Example of abCdefG
output:
The corresponding output is given here. For example:

ABCDEFG

#include<stdio.h>
int main()
{
   
    
    
	char a[30],b[30];
	int i;