C program to print all uppercase and lowercase letters in the alphabet

Write a C program to print all Uppercase and Lowercase letters in the alphabet:

In this example program, we will learn how to print the uppercase and lowercase letters of the alphabet in C programming language. We will use one for loop to print the characters. Let’s take a look into the program :

Method 1: C program with for loop to print the uppercase and lowercase letters:

The following program uses two for loops to print the uppercase and lowercase letters of the alphabet:

#include <stdio.h>

int main()
{
    //1
    char ch;

    //2
    printf("Uppercase characters:\n");
    //3
    for (ch = 'A'; ch <= 'Z'; ch++)
    {
        printf("%c ", ch);
    }

    //4
    printf("\nLowercase characters:\n");
    for (ch = 'a'; ch <= 'z'; ch++)
    {
        printf("%c ", ch);
    }

    return 0;
}

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Explanation :

The commented numbers in the above program denote the step number below:

1. Create one character variable ch.
2. Start printing the uppercase characters.
3. Start a for loop. The loop runs from ch = 'A' to ch = 'Z'. Inside the loop, we are printing the value of ch. It increases the value of ch by 1 on each iteration i.e. the ASCII value of the character defined by the variable ch is increased by 1.
4. The second for loop is printing the lowercase characters. It runs from ch = 'a' to ch = 'z'.

Sample output of the program :

If you run the above program, it will print the below output:

Uppercase characters :
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Lowercase characters :
a b c d e f g h i j k l m n o p q r s t u v w x y z

Method 2: C program with while loop to print the uppercase and lowercase letters:

We can also use two while loops to print the uppercase and lowercase characters of the alphabet. The following program shows how to print the uppercase and lowercase letters with two while loops:

#include <stdio.h>

int main()
{
    char ch = 'A';

    printf("Uppercase characters:\n");

    while (ch <= 'Z')
    {
        printf("%c ", ch);
        ch++;
    }

    ch = 'a';
    printf("\nLowercase characters:\n");
    while (ch <= 'z')
    {
        printf("%c ", ch);
        ch++;
    }

    return 0;
}

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Here, the ch variable is initialized before the loop starts and at the end of the loop, we are incrementing the value of ch by 1. It will print the same output.

Uppercase characters:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
Lowercase characters:
a b c d e f g h i j k l m n o p q r s t u v w x y z

Method 3: How to use it with do...while loop:

We can also write this program with do...while loops. The do...while loop is similar to a while loop. The only difference is that it runs the code in the do block and then checks the while condition. The following program shows how it works:

#include <stdio.h>

int main()
{
    char ch = 'A';

    printf("Uppercase characters:\n");

    do
    {
        printf("%c ", ch);
        ch++;
    } while (ch <= 'Z');

    ch = 'a';
    printf("\nLowercase characters:\n");
    do
    {
        printf("%c ", ch);
        ch++;
    } while (ch <= 'z');

    return 0;
}

Download this program on Github

It will print the same output.

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