C Program to Convert Decimal to Hexadecimal

January 03, 2026

C Program to Check Prime Number Using Efficient Logic

Introduction A prime number is a number that has exactly two distinct positive divisors: 1 and itself. In this program, we check whether a given number is prime or not using a simple and efficient logic. This type of program is commonly used in mathematics, competitive programming, and basic algorithm learning for beginners in C programming. Problem Statement The task is to write a C program that determines whether a given integer is a prime number or not. The program takes a single integer input from the user and analyzes its divisibility. If the number has no divisors other than 1 and itself, it should be identified as a prime number; otherwise, it is not prime. This problem is important in number theory and has practical relevance in areas such as cryptography, data validation, and algorithm design. Algorithm / Logic Explanation To check whether a number is prime, we need to verify that it is not divisible by any number other than 1 and itself. The algorithm follows a si...

✅ C Program to Convert Decimal Number to Hexadecimal

#include <stdio.h>

int main() {
    int num;

    printf("Enter a decimal number: ");
    scanf("%d", &num);

    printf("Hexadecimal: %X\n", num);   // %X prints in uppercase A–F
    printf("Hexadecimal (lowercase): %x\n", num); // %x prints in lowercase a–f

    return 0;
}

📘 Explanation:

This program converts a decimal number into its hexadecimal representation using the printf format specifiers:

%X → prints the hexadecimal value in uppercase (A–F).
%x → prints the hexadecimal value in lowercase (a–f).
For example, decimal 255 will be displayed as FF and ff.

🧾 Sample Output:

Enter a decimal number: 255
Hexadecimal: FF
Hexadecimal (lowercase): ff

🔑 Keywords:

C program decimal to hexadecimal, printf %X and %x, decimal to hex conversion in C, hexadecimal number system C program, beginner C examples

📌 Hashtags:

#CProgramming #HexadecimalConversion #DecimalToHex #CExamples #CodingForBeginners

🔍 Search Description:

This C program converts a decimal number into hexadecimal using printf format specifiers %X and %x. It displays both uppercase and lowercase hexadecimal outputs with examples.

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C Program to Check Prime Number Using Efficient Logic