Diamond pattern in C

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: Diamond Star Pattern

#include<stdio.h> int main() { int num; printf("Enter the number:\n"); scanf("%d",&num); // Upper Half for(int i=1; i<=num; i++) { for(int k=num; k>=i; k--) { printf(" "); } for(int j=i; j>=1; j--) { printf("* "); } printf("\n"); } // Lower Half for(int i=num; i>=1; i--) { for(int k=num; k>=i; k--) { printf(" "); } for(int j=1; j<=i; j++) { printf("* "); } printf("\n"); } return 0; }

📘 Explanation:

This C program prints a full diamond star pattern. It first constructs the top half of the diamond using an upright pyramid of stars with leading spaces for alignment. The bottom half is constructed using an inverted pyramid.

- The outer loops run for `num` lines each for the top and bottom halves. - The inner loops handle spacing and star printing. - Spacing ensures the stars are centered, forming a symmetric diamond shape.

🔍 Sample Output:

Enter the number:
4
    * 
   * * 
  * * * 
 * * * * 
 * * * * 
  * * * 
   * * 
    *

🏷️ Keywords:

C star pattern, diamond pattern in C, full diamond program, half pyramid in C, inverted pyramid, star shape printing in C, C loop practice

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C Program to Check Prime Number Using Efficient Logic