Exercise 2.10 - upper case letters to lower case#
Question#
Rewrite the function lower, which converts upper case letters to lower case, with a conditional expression instead of if-else.
/* Function lower(c) using conditional expression */
#include<stdio.h>
int lower(int c);
int main(void)
{
int c;
while((c=getchar())!=EOF)
{
putchar(lower(c));
}
}
int lower(int c)
{
return c>='A' && c<='Z'? c+'a'-'A':c;
}
Explanation#
In this program we are going to convert upper case letters to lower case. We declare a function called lower in the beginning of the program. When the program enters the while loop it each character it gets to lower:
while((c=getchar())!=EOF)
{
putchar(lower(c));
}
The lower function checks for all the uppercase characters and prints everything in the lowercase. It does this by a conditional statement, where if a upper case character is found, it subtracts ‘A’ to get relative index, adds it to ‘a’ to return corresponding smaller case character, if a lower case character is found, it is simply returned:
return c>='A' && c<='Z'? c+'a'-'A':c;