AI Coding & CSE Fundamentals

💻 Day of the Week Based on Number (1-7)

#include <stdio.h>

int main() {
    int dayNumber;

    printf("Enter a number (1-7): ");
    scanf("%d", &dayNumber);

    if (dayNumber == 1) {
        printf("Sundayn");
    } else if (dayNumber == 2) {
        printf("Mondayn");
    } else if (dayNumber == 3) {
        printf("Tuesdayn");
    } else if (dayNumber == 4) {
        printf("Wednesdayn");
    } else if (dayNumber == 5) {
        printf("Thursdayn");
    } else if (dayNumber == 6) {
        printf("Fridayn");
    } else if (dayNumber == 7) {
        printf("Saturdayn");
    } else {
        printf("Invalid input. Please enter a number between 1 and 7.n");
    }

    return 0;
}

📤 Output:

Enter a number (1-7): 1
Sunday

Enter a number (1-7): 4
Wednesday

Enter a number (1-7): 7
Saturday

Enter a number (1-7): 0
Invalid input. Please enter a number between 1 and 7.

Enter a number (1-7): 8
Invalid input. Please enter a number between 1 and 7.

Enter a number (1-7): 5
Thursday

💻 Calculate Electricity Bill Based on Units

#include <stdio.h>

int main() {
  int units;
  float bill;

  printf("Enter the number of units consumed: ");
  scanf("%d", &units);

  if (units <= 50) {
    bill = units * 0.50;
  } else if (units <= 150) {
    bill = 25 + (units - 50) * 0.75;
  } else if (units <= 250) {
    bill = 100 + (units - 150) * 1.00;
  } else {
    bill = 200 + (units - 250) * 1.25;
  }

  printf("Electricity bill: Rs. %.2fn", bill);

  return 0;
}

📤 Output:

Input: 30
Output: Electricity bill: Rs. 15.00
Input: 100
Output: Electricity bill: Rs. 62.50
Input: 200
Output: Electricity bill: Rs. 150.00
Input: 300
Output: Electricity bill: Rs. 262.50

💻 Check Triangle Type (Equilateral, Isosceles, Scalene)

#include <stdio.h>

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

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

    if (side1 == side2 && side2 == side3) {
        printf("Equilateral trianglen");
    } else if (side1 == side2 || side1 == side3 || side2 == side3) {
        printf("Isosceles trianglen");
    } else {
        printf("Scalene trianglen");
    }

    return 0;
}

📤 Output:

Input: 5 5 5
Output: Enter the lengths of three sides of a triangle: Equilateral triangle

Input: 3 4 5
Output: Enter the lengths of three sides of a triangle: Scalene triangle

Input: 2 2 3
Output: Enter the lengths of three sides of a triangle: Isosceles triangle

💻 Simple Grade Calculator (A, B, C, D, F)

#include <stdio.h>

int main() {
  int score;

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

  if (score >= 90) {
    printf("Grade: An");
  } else if (score >= 80) {
    printf("Grade: Bn");
  } else if (score >= 70) {
    printf("Grade: Cn");
  } else if (score >= 60) {
    printf("Grade: Dn");
  } else {
    printf("Grade: Fn");
  }

  return 0;
}

📤 Output:

Input: 95
Output: Grade: A

Input: 82
Output: Grade: B

Input: 75
Output: Grade: C

Input: 61
Output: Grade: D

Input: 50
Output: Grade: F

💻 Find Maximum of Three Numbers

#include <stdio.h>

int main() {
  int num1, num2, num3;

  printf("Enter three numbers: ");
  scanf("%d %d %d", &num1, &num2, &num3);

  if (num1 >= num2 && num1 >= num3) {
    printf("Maximum number is: %d", num1);
  } else if (num2 >= num1 && num2 >= num3) {
    printf("Maximum number is: %d", num2);
  } else {
    printf("Maximum number is: %d", num3);
  }

  printf("n");
  return 0;
}

📤 Output:

Input: 10 5 8
Output: Enter three numbers: Maximum number is: 10

Input: 5 12 3
Output: Enter three numbers: Maximum number is: 12

Input: 2 7 15
Output: Enter three numbers: Maximum number is: 15

🔧 Conditional Statements - else-if ladder

💻 Check if String Starts with Vowel

#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main() {
    char str[100];

    printf("Enter a string: ");
    scanf("%s", str);

    char firstChar = tolower(str[0]);

    if (firstChar == 'a' || firstChar == 'e' || firstChar == 'i' || firstChar == 'o' || firstChar == 'u') {
        printf("String starts with a vowel.n");
    } else {
        printf("String does not start with a vowel.n");
    }

    return 0;
}

📤 Output:

Input: apple
Output: String starts with a vowel.

Input: Banana
Output: String does not start with a vowel.

Input: Example
Output: String starts with a vowel.

Input: orange
Output: String starts with a vowel.

Input: umbrella
Output: String starts with a vowel.

Input: Test
Output: String does not start with a vowel.

💻 Check if Number is Palindrome

#include <stdio.h>

int main() {
    int n, reversedInteger = 0, remainder, originalInteger;

    printf("Enter an integer: ");
    scanf("%d", &n);

    originalInteger = n;

    while (n != 0) {
        remainder = n % 10;
        reversedInteger = reversedInteger * 10 + remainder;
        n /= 10;
    }

    if (originalInteger == reversedInteger)
        printf("%d is a palindrome.", originalInteger);
    else
        printf("%d is not a palindrome.", originalInteger);

    return 0;
}

📤 Output:

Input: 121
Output: 121 is a palindrome.

Input: 123
Output: 123 is not a palindrome.

Input: 3553
Output: 3553 is a palindrome.

Input: 12345
Output: 12345 is not a palindrome.

💻 Check if Character is Uppercase or Lowercase

#include <stdio.h>

int main() {
  char ch;

  printf("Enter a character: ");
  scanf(" %c", &ch);

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

  return 0;
}

📤 Output:

Input: G
Output: Enter a character: G is an uppercase character.

Input: g
Output: Enter a character: g is a lowercase character.

Input: 5
Output: Enter a character: 5 is not an alphabet.

💻 Check if Triangle is Valid

#include <stdio.h>

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

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

    if (side1 + side2 > side3 && side1 + side3 > side2 && side2 + side3 > side1) {
        printf("Triangle is valid.n");
    } else {
        printf("Triangle is not valid.n");
    }

    return 0;
}

📤 Output:

Input: 3 4 5
Output: Triangle is valid.

Input: 1 2 5
Output: Triangle is not valid.

Input: 7 10 5
Output: Triangle is valid.

💻 Check if Number is Prime

#include <stdio.h>
#include <stdbool.h>

int main() {
  int num, i;
  bool isPrime = true;

  printf("Enter a positive integer: ");
  scanf("%d", &num);

  if (num <= 1) {
    isPrime = false;
  } else {
    for (i = 2; i <= num / 2; ++i) {
      if (num % i == 0) {
        isPrime = false;
        break; // Exit the loop if not prime
      }
    }
  }

  if (isPrime) {
    printf("%d is a prime number.n", num);
  } else {
    printf("%d is not a prime number.n", num);
  }

  return 0;
}

📤 Output:

Input: 7
Output: 7 is a prime number.

Input: 12
Output: 12 is not a prime number.

Input: 1
Output: 1 is not a prime number.

Input: 2
Output: 2 is a prime number.

Input: 0
Output: 0 is not a prime number.

Input: -5
Output: -5 is not a prime number.

💻 Check if Person is Eligible to Vote

#include <stdio.h>

int main() {
    int age;

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

    if (age >= 18) {
        printf("You are eligible to vote!n");
    } else {
        printf("You are not eligible to vote yet.n");
    }

    return 0;
}

📤 Output:

Input: 25
Output: Enter your age: You are eligible to vote!

Input: 16
Output: Enter your age: You are not eligible to vote yet.

💻 Check Profit or Loss from Cost and Sell Price

#include <stdio.h>

int main() {
  float costPrice, sellingPrice, profit, loss;

  printf("Enter cost price: ");
  scanf("%f", &costPrice);

  printf("Enter selling price: ");
  scanf("%f", &sellingPrice);

  if (sellingPrice > costPrice) {
    profit = sellingPrice - costPrice;
    printf("Profit: %.2fn", profit);
  } else if (costPrice > sellingPrice) {
    loss = costPrice - sellingPrice;
    printf("Loss: %.2fn", loss);
  } else {
    printf("No profit, no loss.n");
  }

  return 0;
}

📤 Output:

Input: 100.00
Input: 120.00
Output: Profit: 20.00

Input: 100.00
Input: 80.00
Output: Loss: 20.00

Input: 100.00
Input: 100.00
Output: No profit, no loss.

💻 Check if Character is Alphabet or Digit

#include <stdio.h>

int main() {
    char ch;

    printf("Enter a character: ");
    scanf(" %c", &ch);

    if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
        printf("%c is an alphabet.n", ch);
    } else if (ch >= '0' && ch <= '9') {
        printf("%c is a digit.n", ch);
    } else {
        printf("%c is not an alphabet or a digit.n", ch);
    }

    return 0;
}

📤 Output:

Input: A
Output: Enter a character: A is an alphabet.

Input: 5
Output: Enter a character: 5 is a digit.

Input: $
Output: Enter a character: $ is not an alphabet or a digit.

💻 Check if Number is Even or Odd

#include <stdio.h>

int main() {
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    if (number % 2 == 0) {
        printf("%d is even.n", number);
    } else {
        printf("%d is odd.n", number);
    }

    return 0;
}

📤 Output:

Input: 7
Output: 7 is odd.

Input: 12
Output: 12 is even.

Input: 0
Output: 0 is even.

Input: -5
Output: -5 is odd.

Input: -8
Output: -8 is even.

💻 Check if Number is Positive or Negative

#include <stdio.h>

int main() {
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    if (number > 0) {
        printf("The number is positive.n");
    } else if (number < 0) {
        printf("The number is negative.n");
    } else {
        printf("The number is zero.n");
    }

    return 0;
}

📤 Output:

Input: 5
Output: The number is positive.

Input: -3
Output: The number is negative.

Input: 0
Output: The number is zero.

🔧 Conditional Statements - if-else

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💻 Check if String is Empty

#include <stdio.h>
#include <string.h>

int main() {
    char str[100];
    printf("Enter a string: ");
    scanf("%s", str);

    if (strlen(str) == 0) {
        printf("The string is empty.n");
    } else {
        printf("The string is not empty.n");
    }

    return 0;
}

📤 Output:

Input: hello
Output: The string is not empty.

Input:
Output: The string is empty.

Input: abcdefghijklmnopqrstuvwxyz
Output: The string is not empty.