tolower in C Programming

The tolower() function is one of the Standard Library Function available in C language, which is used to convert the user specified character into Lowercase character. The syntax of the tolower in C Programming language is

C tolower Function syntax

Following function will accept the character as the parameter, and convert the given character to lowercase using the tolower in C.

tolower(chars)

tolower in C Programming Example

The tolower method is used to convert the given character to lowercase. This C program allows the user to enter any character, and convert that character to lowercase using the tolower function.

//Example for C tolower
#include <stdio.h>
#include <ctype.h>

int main()
{
   char ch;
   printf("Please Enter Any Character: \n");
   scanf("%c", &ch);

   printf("\n Your character is converted into Lower Case = %c", tolower(ch));         
}

OUTPUT

ANALYSIS

First we declared one character variable ch

char ch;

Below statement will asked to enter any character. And then we are assigning the user entered character to ch variable

printf("Please Enter Any Character: \n");
scanf("%c", &ch);

Next, we used the tolower() function directly inside the printf statements to print the output. Following statement will convert the character in ch variable to lowercase

printf("\n Your character is converted into Lower Case = %c", tolower(ch));

Above code will definitely convert the given character to lowercase, but what if we enter the numeric value

As you can see it is not throwing any error, which is not good in real-time.

tolower in C Programming Example 2

A better approach to above mentioned C program

//Example for C tolower
#include <stdio.h>
#include <ctype.h>

int main()
{
   char ch;
   printf("Please Enter Any Character: \n");
   scanf("%c", &ch);

   if(isalpha(ch))
   {
      printf("\n Your character is converted into Lower Case = %c", tolower(ch));         
   }
   else
   {
      printf("\n Please Enter a Valid character"); 
   }
}

OUTPUT

Let me enter the numeric value

ANALYSIS

Here we added the If Statement to check whether the character is between ‘A’ and ‘Z’. If the condition is True, it will convert the given character to Lowercase using below statement

printf("\n Your character is converted into Lower Case = %c", tolower(ch));

If the above condition is FALSE then the given character is not Alphabet So, it will print below statement

printf("\n Please Enter a Valid character");

TIP: Please refer C Program to Convert Character to Lowercase article to understand, How to convert the character to lowercase without using the tolower function.