Convert Uppercase to Lowercase in C

This section will discuss the different programs to convert the uppercase letters (character or strings) into lowercase in the C programming language. The uppercase letter is the capital letter of the alphabet. For example, capital letters are A, B, C, D, …, X, Y, Z. Similarly, a lowercase letter is represented by the small letter of the alphabet. For example, small letters are a, b, c, d, e…., w, x, y, z.

When we convert the capital letters or strings into lowercase using the ASCII codes, the process converts the uppercase to the lowercase letters in C programming. The ASCII value of the uppercase letter (A -Z) is ranging from 65 to 90, and the ASCII value of the lowercase letter (a -z) is ranging from 97 to 122.

For example, we have the capital letter 'A' and want to convert it into lowercase letter 'a', we need to add 32 to the ASCII value of A (65) that returns character 'a' whose ASCII value is 97 (65 + 32). Similarly, we can convert the uppercase string 'HELLO' into the lowercase string 'hello'.

Program to convert the uppercase character into lowercase

Let's write a program to convert the uppercase character into lowercase character in C programming language.

Program1.c

Output

Enter the Upper Case Character: A
 A character in Lower case is: a
 Enter the Lower Case Character: z
 z character in the Upper case is: Z

Program to convert the uppercase string into lower case using for loop

Let's write a simple program to convert the uppercase string into lowercase using for loop in the C Programming.

Program2.c

Output

Enter the string: WELCOME

 Upper Case to Lower case string is: welcome

Program to convert the uppercase string into lower case using while loop

Let's consider an example to print the lowercase string from uppercase using while loop in C programming.

Program3.c

Output

Enter an upper case string: CPROGRAMMING

 The lowercase string is: cprogramming

Program to convert the uppercase string into lowercase using the strlwr() function

Strlwr() function: The strlwr() function is a predefined function of the string library used to convert the uppercase string into the lowercase by passing the given string as an argument to return the lowercase string.

Syntax

The strlwr() function has a upr argument representing the uppercase string, and the strlwr() function takes upr argument to return a lowercase string.

Let's create a program to convert the uppercase string into the lowercase using the built-in strlwr() function in C programming.

Program4.c

Output

Enter the upper case string: GOOD BYE

 The lowercase string is: good bye

Program to convert the uppercase string into lowercase using the user-defined function

Let's consider an example to convert the uppercase string into lowercase using the user-defined function in C programming.

Program5.c

Output

Enter the upper case string: JAVATPOINT

 The lowercase string is: javatpoint

Program to convert the uppercase string into lowercase using the recursion function

Let's consider an example to print the lowercase string from uppercase using the recursion function in the C programming.

Program6.c

Output

Enter the upper case string: C PROGRAMMING LANGUAGE

The lowercase string is: c programming language