if condition — C language programs

7 min readJun 27, 2026

Print number is greater or not

#include<stdio.h>

int main()
{
    int num; 
    printf("Enter any number ");
    scanf("%d", &num);
    if(num >100)
    {
        printf("Yes ");
    }
    else{
        printf("No");
    }
}

Number is Positive, Negative or Zero

#include<stdio.h>
int main()
{
    int num; 
    printf("Enter any number ");
    scanf("%d", &num);

    if(num == 0 )
    {
        printf("Zero");
    }
    else if(num > 0 )
    {
        printf("Positive");
    }
    else {
        printf("Negative");

    }
}

Number is odd or even

#include<stdio.h>

int main()
{
    int num; 
    printf("Enter any number ");
    scanf("%d", &num);
    
    if (num % 2 == 0 )
    {
        printf("Even ");
    }
    else
    {
        printf("Odd"); 
    }
}

Number is divisible or not

#include<stdio.h>

int main()
{
    int num1, num2; 
    printf("Enter any number1 and number 2 ");
    scanf("%d%d", &num1, &num2);
    
    if (num1 % num2 == 0 )
    {
        printf("Yes, Divible");
    }
    else
    {
        printf("No "); 
    }
}

Calculate grade

#include<stdio.h>

int main()
{
    double sub1, sub2, sub3;
    double sum , per ;
    char grade;
    printf("Enter three subject marks ");
    scanf("%lf%lf%lf", &sub1, &sub2, &sub3);
    sum = sub1 + sub2 + sub3;
    per = sum/210 *100 ; // percentage 70MAX Marks 

   if (per >=80)
        grade = 'A';
    else if (per >=60)
        grade = 'B';
    else if (per >=40)
        grade = 'C';
    else
        grade = 'D';
    printf("Total Marks = %0.2lf \n",sum);
    printf("Percentage  = %0.2lf \n", per);
    printf("Grade  = %c", grade);
    
}

C program to find maximum between two numbers

#include <stdio.h>
int main()
{
    int num1, num2;
    printf("Enter two numbers: ");
    scanf("%d%d", &num1, &num2);
    if(num1 > num2)
    {
        printf("%d is maximum", num1);        
    }
    else if(num2 > num1)
    {
        printf("%d is maximum", num2);
    }
    else 
    {
        printf("Both are equal");
    }
    return 0;
}

Largest from three numbers

#include<stdio.h>

int main()
{
    int a , b , c;
    scanf("%d%d%d", &a, &b, &c);
    
     if (a  > b)
     {
        if (a > c)
            printf("A ");
        else    
            printf("C");
     }
     else 
     {
        if ( b > c)
            printf("B ");
        else
            printf("C");
     }

        
}

Largest from three numbers (using logical operators)

#include<stdio.h>

int main()
{
    int a , b , c;
    scanf("%d%d%d", &a, &b, &c);
    
    if (a > b && a > c)
        printf("A");
    else if (b>a && b > c)
        printf("B");
    else if (c > a && c > b)
        printf("C");
        
}

C program to read the height of a person and the print person is taller, dwarf, or average height person

#include <stdio.h>

int main()
{
    double height = 0;

    printf("Enter Height (in centimetres): ");
    scanf("%lf", &height);

    if ((height >= 150.0) && (height <= 170.0)) {
        printf("Person is average height person");
    }
    else if ((height > 170.0) && (height <= 195.0)) {
        printf("Person is taller");
    }
    else if (height < 150.0) {
        printf("Person is dwarf");
    }
    else
        printf("Abnormal height \n");

    return 0;
}

C Program to Check Leap Year using nested if

#include<stdio.h>

int main()
{

    int year ;
    printf("enter year ");
    scanf("%d", &year );
    if (year % 100 ==0 )
    {
        if(year % 400 == 0)
            printf("leap year");
        else 
            printf("not a leap year ");
    }
    else
    {
        if (year % 4 == 0)
            printf("leap year");
        else 
            printf("not a leap year ");
    }
}

C Program to Check Leap Year using logical operator

#include <stdio.h>

int main() {
    
    // Declare an integer variable
    int year;
    printf("Enter a year: ");
    scanf("%d", &year);

    // Check year is leap or not using if else statement
    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
        printf("%d is a leap year.", year);
    } else {
        printf("%d is not a leap year.", year);
    }

    return 0;
}

Check Vowel or Consonant in C

#include <stdio.h>

int main() {
    
    // Declare character variable
    char ch;
    printf("Enter a character: ");
    scanf("%c", &ch);

    // Check if the character is a vowel 
    // using if-else
    if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' ||
        ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') {
        printf("%c is a vowel.", ch);
    } else {
        printf("%c is a consonant.", ch);
    }

    return 0;
}

Program to check whether a character is alphabet or not

#include <stdio.h>

int main()
{
    char ch;
    
    /* Input a character from user */
    printf("Enter any character: ");
    scanf("%c", &ch);

    if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))
    {
        printf("Character is an ALPHABET.");
    }
    else
    {
        printf("Character is NOT ALPHABET.");
    }

    return 0;
}

Program to check whether a character is alphabet, digit or special character


//Program to check whether a character is alphabet, digit or special character
#include <stdio.h>
int main()
{
    int num1, num2;
    printf("Enter two numbers: ");
    scanf("%d%d", &num1, &num2);
    if(num1 > num2)
    {
        printf("%d is maximum", num1);        
    }
    else if(num2 > num1)
    {
        printf("%d is maximum", num2);
    }
    else 
    {
        printf("Both are equal");
    }
    return 0;
}

C program to check whether a character is Uppercase or Lowercase

#include <stdio.h>

int main()
{
    char ch;

    /* Input character from user */
    printf("Enter any character: ");
    scanf("%c", &ch);


    if(ch >= 'A' && ch <= 'Z')
    {
        printf("'%c' is uppercase alphabet.", ch);
    }
    else if(ch >= 'a' && ch <= 'z')
    {
        printf("'%c' is lowercase alphabet.", ch);
    }
    else
    {
        printf("'%c' is not an alphabet.", ch);
    }

    return 0;
}

C program to enter week number and print day of week

#include <stdio.h>

int main()
{
    int week;

    /* Input week number from user */
    printf("Enter week number (1-7): ");
    scanf("%d", &week);


    if(week == 1)
    {
        printf("Monday");
    }
    else if(week == 2)
    {
        printf("Tuesday");
    }
    else if(week == 3)
    {
        printf("Wednesday");
    }
    else if(week == 4)
    {
        printf("Thursday");
    }
    else if(week == 5)
    {
        printf("Friday");
    }
    else if(week == 6)
    {
        printf("Saturday");
    }
    else if(week == 7)
    {
        printf("Sunday");
    }
    else
    {
        printf("Invalid Input! Please enter week number between 1-7.");
    }

    return 0;
}

C program to calculate profit or loss

#include <stdio.h>

int main()
{
    int cp,sp, amt; 
    
    /* Input cost price and selling price of a product */
    printf("Enter cost price: ");
    scanf("%d", &cp);
    printf("Enter selling price: ");
    scanf("%d", &sp);
    
    if(sp > cp)
    {
        /* Calculate Profit */
        amt = sp - cp;
        printf("Profit = %d", amt);
    }
    else if(cp > sp)
    {
        /* Calculate Loss */
        amt = cp - sp;
        printf("Loss = %d", amt);
    }
    else
    {
        /* Neither profit nor loss */
        printf("No Profit No Loss.");
    }

    return 0;
}

C program to find all roots of a quadratic equation

#include <stdio.h>
#include <math.h> /* Used for sqrt() */

int main()
{
    float a, b, c;
    float root1, root2, imaginary;
    float discriminant;
    
    printf("Enter values of a, b, c of quadratic equation (aX^2 + bX + c): ");
    scanf("%f%f%f", &a, &b, &c);
    
    /* Find discriminant of the equation */
    discriminant = (b * b) - (4 * a * c);
    
   
    /* Find the nature of discriminant */
    if(discriminant > 0)
    {
        root1 = (-b + sqrt(discriminant)) / (2*a);
        root2 = (-b - sqrt(discriminant)) / (2*a);

        printf("Two distinct and real roots exists: %.2f and %.2f", root1, root2);
    }
    else if(discriminant == 0)
    {
        root1 = root2 = -b / (2 * a);

        printf("Two equal and real roots exists: %.2f and %.2f", root1, root2);
    }
    else if(discriminant < 0)
    {
        root1 = root2 = -b / (2 * a);
        imaginary = sqrt(-discriminant) / (2 * a);

        printf("Two distinct complex roots exists: %.2f + i%.2f and %.2f - i%.2f", 
                root1, imaginary, root2, imaginary);
    }

    return 0;
}

C program to check whether triangle is equilateral, scalene or isosceles

#include <stdio.h>

int main()
{
    int side1, side2, side3;

    /* Input sides of a triangle */
    printf("Enter three sides of triangle: ");
    scanf("%d%d%d", &side1, &side2, &side3);

    if(side1==side2 && side2==side3) 
    {
        /* If all sides are equal */
        printf("Equilateral triangle.");
    }
    else if(side1==side2 || side1==side3 || side2==side3) 
    {
        /* If any two sides are equal */
        printf("Isosceles triangle.");
    }
    else 
    {
        /* If none sides are equal */
        printf("Scalene triangle.");
    }

    return 0;
}

C program to check whether triangle is valid or not if sides are given

#include <stdio.h>

int main()
{
    int side1, side2, side3;

    /* Input three sides of a triangle */
    printf("Enter three sides of triangle: \n");
    scanf("%d%d%d", &side1, &side2, &side3);
    
    if((side1 + side2) > side3)
    {
        if((side2 + side3) > side1)
        {
            if((side1 + side3) > side2) 
            {
                /*
                 * If side1 + side2 > side3 and
                 *    side2 + side3 > side1 and
                 *    side1 + side3 > side2 then
                 * the triangle is valid.
                 */
                printf("Triangle is valid.");
            }
            else
            {
                printf("Triangle is not valid.");
            }
        }
        else
        {
            printf("Triangle is not valid.");
        }
    }
    else
    {
        printf("Triangle is not valid.");
    }

    return 0;
}

C program to check whether triangle is valid or not if angles are given

#include <stdio.h>

int main()
{
    int angle1, angle2, angle3, sum;

    /* Input all three angles of triangle */
    printf("Enter three angles of triangle: \n");
    scanf("%d%d%d", &angle1, &angle2, &angle3);

    sum = angle1 + angle2 + angle3; 

    if(sum == 180 && angle1 > 0 && angle2 > 0 && angle3 > 0) 
    {
        printf("Triangle is valid.");
    }
    else
    {
        printf("Triangle is not valid.");
    }

    return 0;
}

C program to enter basic salary and calculate gross salary of an employee

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Basic Salary <= 10000 : HRA = 20%, DA = 80%
Basic Salary is between 10001 to 20000 : HRA = 25%, DA = 90%
Basic Salary >= 20001 : HRA = 30%, DA = 95%

#include <stdio.h>
int main()
{
    float basic, gross, da, hra;

    /* Input basic salary of employee */
    printf("Enter basic salary of an employee: ");
    scanf("%f", &basic);
    if(basic <= 10000)
    {
        da  = basic * 0.8;
        hra = basic * 0.2;
    }
    else if(basic <= 20000)
    {
        da  = basic * 0.9;
        hra = basic * 0.25;
    }
    else
    {
        da  = basic * 0.95;
        hra = basic * 0.3;
    }
    gross = basic + hra + da;
    printf("GROSS SALARY OF EMPLOYEE = %.2f", gross);

    return 0;
}