C Conditional Statement Examples

Conditional statements in C help control program flow by making decisions based on conditions. Using if, else if, else, and nested if-else, programs execute different code blocks depending on whether conditions are true or false.

26. C Program to Check Even or Odd 
#include <stdio.h>
int main(void){
    int n;
    printf("Enter number: ");
    scanf("%d",&n);
    if(n%2==0){
        printf("Even\n");
    }else{
        printf("Odd\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int n;
    printf("Enter number: ");
    scanf("%d",&n);
    if(n>0){
        printf("Positive\n");
    }else if(n<0){
        printf("Negative\n");
    }else{
        printf("Zero\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int a,b;
    printf("Enter two numbers: ");
    scanf("%d%d",&a,&b);
    if(a>b){
        printf("%d is larger\n",a);
    }else if(b>a){
        printf("%d is larger\n",b);
    }else{
        printf("Both are equal\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int a,b,c;
    printf("Enter three numbers: ");
    scanf("%d%d%d",&a,&b,&c);
    if(a>=b && a>=c){
        printf("%d is largest\n",a);
    }else if(b>=a && b>=c){
        printf("%d is largest\n",b);
    }else{
        printf("%d is largest\n",c);
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int n;
    printf("Enter number: ");
    scanf("%d",&n);
    if(n%5==0 && n%11==0){
        printf("Divisible by 5 and 11\n");
    }else{
        printf("Not divisible by both\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    float cp,sp;
    printf("Enter cost and selling price: ");
    scanf("%f%f",&cp,&sp);
    if(sp>cp){
        printf("Profit: %.2f\n",sp-cp);
    }else if(cp>sp){
        printf("Loss: %.2f\n",cp-sp);
    }else{
        printf("No profit no loss\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int n;
    printf("Enter number: ");
    scanf("%d",&n);
    if(n<0){
        n=-n;
    }
    printf("Absolute value: %d\n",n);
    return 0;
}
#include <stdio.h>
int main(void){
    float units,bill;
    printf("Enter units: ");
    scanf("%f",&units);
    if(units<=100){
        bill=units*1.5;
    }else if(units<=200){
        bill=100*1.5+(units-100)*2;
    }else{
        bill=100*1.5+100*2+(units-200)*3;
    }
    printf("Bill = ₹%.2f\n",bill);
    return 0;
}
#include <stdio.h>
int main(void){
    char ch;
    printf("Enter letter: ");
    scanf(" %c",&ch);
    if(ch=='A'||ch=='E'||ch=='I'||ch=='O'||ch=='U'||ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u'){
        printf("Vowel\n");
    }else{
        printf("Consonant\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    char ch;
    printf("Enter character: ");
    scanf(" %c",&ch);
    if((ch>='A' && ch<='Z')||(ch>='a' && ch<='z')){
        printf("Alphabet\n");
    }else{
        printf("Not alphabet\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    char ch;
    printf("Enter character: ");
    scanf(" %c",&ch);
    if(ch>='A' && ch<='Z'){
        printf("Uppercase\n");
    }else if(ch>='a' && ch<='z'){
        printf("Lowercase\n");
    }else{
        printf("Not alphabet\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    char ch;
    printf("Enter character: ");
    scanf(" %c",&ch);
    if((ch>='A' && ch<='Z') || (ch>='a' && ch<='z')){
        printf("Alphabet\n");
    }else if(ch>='0' && ch<='9'){
        printf("Digit\n");
    }else{
        printf("Special character\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int y;
    printf("Enter year: ");
    scanf("%d",&y);
    if((y%4==0 && y%100!=0) || y%400==0){
        printf("Leap year\n");
    }else{
        printf("Not leap year\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int marks;
    printf("Enter marks: ");
    scanf("%d",&marks);
    if(marks>=90){
        printf("Grade A\n");
    }else if(marks>=75){
        printf("Grade B\n");
    }else if(marks>=60){
        printf("Grade C\n");
    }else if(marks>=40){
        printf("Grade D\n");
    }else{
        printf("Fail\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int a,b,c;
    printf("Enter 3 sides: ");
    scanf("%d%d%d",&a,&b,&c);
    if(a+b>c && b+c>a && c+a>b){
        printf("Valid triangle\n");
    }else{
        printf("Invalid triangle\n");
    }
    return 0;
}
#include <stdio.h>
#include <math.h>
int main(void){
    float a,b,c,d;
    printf("Enter a,b,c: ");
    scanf("%f%f%f",&a,&b,&c);
    d=b*b-4*a*c;
    if(d>0){
        printf("Two real roots: %.2f and %.2f\n",(-b+sqrt(d))/(2*a),(-b-sqrt(d))/(2*a));
    }else if(d==0){
        printf("One real root: %.2f\n",-b/(2*a));
    }else{
        printf("Imaginary roots\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    int d;
    printf("Enter day number (1-7): ");
    scanf("%d",&d);
    if(d==1){
        printf("Monday\n");
    }else if(d==2){
        printf("Tuesday\n");
    }else if(d==3){
        printf("Wednesday\n");
    }else if(d==4){
        printf("Thursday\n");
    }else if(d==5){
        printf("Friday\n");
    }else if(d==6){
        printf("Saturday\n");
    }else if(d==7){
        printf("Sunday\n");
    }else{
        printf("Invalid\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    float t;
    printf("Enter temperature: ");
    scanf("%f",&t);
    if(t<0){
        printf("Freezing\n");
    }else if(t<=20){
        printf("Cold\n");
    }else if(t<=35){
        printf("Warm\n");
    }else{
        printf("Hot\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
    char op;
    float a,b;
    printf("Enter operator (+,-,*,/): ");
    scanf(" %c",&op);
    printf("Enter two numbers: ");
    scanf("%f%f",&a,&b);
    if(op=='+'){
        printf("Result = %.2f\n",a+b);
    }else if(op=='-'){
        printf("Result = %.2f\n",a-b);
    }else if(op=='*'){
        printf("Result = %.2f\n",a*b);
    }else if(op=='/'){
        printf("Result = %.2f\n",a/b);
    }else{
        printf("Invalid operator\n");
    }
    return 0;
}
#include <stdio.h>
int main(void){
int num;
// Prompt the user for input
printf("Enter a number: ");
scanf("%d",&num);
// Check if number is whole (0 and above)
if(num>=0){
printf("It is a Whole number.\n");
// Check if number is natural (positive integers only)
if(num>0){
printf("It is also a Natural number.\n");
}
// Check even or odd
if(num%2==0){
printf("It is an Even number.\n");
}else{
printf("It is an Odd number.\n");
}
}else{
printf("It is neither a Whole number nor a Natural number.\n");
}
return 0;
}
#include <stdio.h>

int main() {
    int a, b, c;

    printf("Enter three sides of triangle: ");
    scanf("%d %d %d", &a, &b, &c);

    if (a + b > c && a + c > b && b + c > a) {
        // Valid triangle
        if (a == b && b == c) {
            printf("Equilateral Triangle\n");
        } else if (a == b || b == c || a == c) {
            printf("Isosceles Triangle\n");
        } else {
            printf("Scalene Triangle\n");
        }
    } else {
        printf("Not a valid triangle\n");
    }

    return 0;
}
#include <stdio.h>

int main() {
    int choice;
    float a, b;

    // input comes silently from STDIN
    scanf("%d", &choice);
    scanf("%f %f", &a, &b);

    printf("Menu:\n1.Add\n2.Subtract\n3.Multiply\n4.Divide\n");

    if (choice == 1)
        printf("Result = %.2f\n", a + b);
    else if (choice == 2)
        printf("Result = %.2f\n", a - b);
    else if (choice == 3)
        printf("Result = %.2f\n", a * b);
    else if (choice == 4 && b != 0)
        printf("Result = %.2f\n", a / b);
    else
        printf("Error\n");

    return 0;
}
#include <stdio.h>

int main() {
    int year;

    printf("Enter year: ");
    scanf("%d", &year);

    if (year % 4 == 0) {
        // Year divisible by 4
        if (year % 100 == 0) {
            // Century year
            if (year % 400 == 0) {
                printf("Leap Year\n");
            } else {
                printf("Not a Leap Year\n");
            }
        } else {
            printf("Leap Year\n");
        }
    } else {
        printf("Not a Leap Year\n");
    }

    return 0;
}
#include <stdio.h>

int main() {
    int age;
    char citizenship;

    printf("Enter age: ");
    scanf("%d", &age);

    printf("Are you an Indian citizen? (Y/N): ");
    scanf(" %c", &citizenship);

    if (age >= 18) {
        // Nested condition for citizenship
        if (citizenship == 'Y' || citizenship == 'y') {
            printf("You are eligible to vote\n");
        } else {
            printf("Citizenship required to vote\n");
        }
    } else {
        printf("You are not eligible to vote\n");
    }

    return 0;
}
#include <stdio.h>

int main() {
    int a, b, c;

    printf("Enter three numbers: ");
    scanf("%d %d %d", &a, &b, &c);

    // First if checks a
    if (a > b) {
        // Nested if checks a with c
        if (a > c) {
            printf("Largest number is %d\n", a);
        } else {
            printf("Largest number is %d\n", c);
        }
    } else {
        // Nested if checks b with c
        if (b > c) {
            printf("Largest number is %d\n", b);
        } else {
            printf("Largest number is %d\n", c);
        }
    }

    return 0;
}
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