Program to convert lower case to upper case

//Program to convert lower case to upper case #include<stdio.h> #include<conio.h> #include<string.h> #include<process.h> void main() { char str[50]; int i; clrscr(); printf("Enter string in small letters : "); gets(str); for(i=0;str[i]!=NULL;i++) { if(str[i]<=97||str[i]>=122) { str[i]=str[i]; } else str[i]=str[i]-32; } str[i]=NULL; puts(str); getch(); }