Basic Arithmetic Evaluator

Construct a function that evaluates a simple mathematical expression given two integer operands and a character operator.

#include <stdio.h>

int compute(int val1, int val2, char op);

int main() {
    int x, y;
    char sym;
    printf("Enter expression (e.g., 5+3): ");
    scanf("%d%c%d", &x, &sym, &y);
    int outcome = compute(x, y, sym);
    printf("Result: %d\n", outcome);
    return 0;
}

int compute(int val1, int val2, char op) {
    if (op == '+') return val1 + val2;
    if (op == '-') return val1 - val2;
    if (op == '*') return val1 * val2;
    if (op == '/') return val1 / val2;
    if (op == '%') return val1 % val2;
    return 0;
}

Prime Number Verification

Design a routine that checks whether an input integer is a prime number, returning 1 for true and 0 for false.

#include <stdio.h>
#include <math.h>

int checkPrime(int num);

int main() {
    int num;
    printf("Enter an integer: ");
    scanf("%d", &num);
    printf("%d\n", checkPrime(num));
    return 0;
}

int checkPrime(int num) {
    if (num <= 1) return 0;
    int divisor = 2;
    while (divisor * divisor <= num) {
        if (num % divisor == 0) {
            return 0;
        }
        divisor++;
    }
    return 1;
}

Array Element Accumulator

Write a function that takes an integer array and its size, returning the sum of all its elements.

#include <stdio.h>

int accumulate(int arr[], int size);

int main() {
    int dataset[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    int total = accumulate(dataset, 10);
    printf("Total: %d\n", total);
    return 0;
}

int accumulate(int arr[], int size) {
    int total = 0;
    for (int i = 0; i < size; i++) {
        total += arr[i];
    }
    return total;
}

Optimized Bubble Sort

Implement the bubble sort algorithm with an early-exit optimization if no swaps occur during a pass.

#include <stdio.h>

void sortArray(int data[], int len);

int main() {
    int data[] = {20, 40, 10, 5, 50, 30};
    sortArray(data, 6);
    for (int i = 0; i < 6; i++) {
        printf("%d ", data[i]);
    }
    return 0;
}

void sortArray(int data[], int len) {
    for (int i = 0; i < len - 1; i++) {
        int swapped = 0;
        for (int j = 0; j < len - i - 1; j++) {
            if (data[j] > data[j + 1]) {
                int temp = data[j];
                data[j] = data[j + 1];
                data[j + 1] = temp;
                swapped = 1;
            }
        }
        if (!swapped) break;
    }
}

Character Frequency Analyzer

Create a function that categorizes characters in a string into uppercace letters, lowercase letters, digits, spaces, and other characters, tallying each category.

#include <stdio.h>

void analyzeChars(const char text[], int counts[]);

int main() {
    char text[100];
    int counts[5] = {0}; // upper, lower, digit, space, other
    printf("Enter a string: ");
    fgets(text, sizeof(text), stdin);
    analyzeChars(text, counts);
    printf("Uppercase: %d\n", counts[0]);
    printf("Lowercase: %d\n", counts[1]);
    printf("Digits: %d\n", counts[2]);
    printf("Spaces: %d\n", counts[3]);
    printf("Others: %d\n", counts[4]);
    return 0;
}

void analyzeChars(const char text[], int counts[]) {
    int i = 0;
    while (text[i] != '\0') {
        if (text[i] >= 'A' && text[i] <= 'Z') counts[0]++;
        else if (text[i] >= 'a' && text[i] <= 'z') counts[1]++;
        else if (text[i] >= '0' && text[i] <= '9') counts[2]++;
        else if (text[i] == ' ' || text[i] == '\t') counts[3]++;
        else if (text[i] != '\n') counts[4]++;
        i++;
    }
}

String Length Determination

Implement a function equivalent to strlen that counts the number of characters in a string before the null terminater.

#include <stdio.h>

int getLength(const char str[]);

int main() {
    char str[100];
    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin);
    int len = getLength(str);
    if (len > 0 && str[len - 1] == '\n') str[len - 1] = '\0';
    printf("Length: %d\n", getLength(str));
    return 0;
}

int getLength(const char str[]) {
    int len = 0;
    while (str[len] != '\0') {
        len++;
    }
    return len;
}

Uppercase to Lowercase Conversion

Write a function that modifies a string in-place, converting all uppercase alphabetic characters to their lowercase equivalents.

#include <stdio.h>

void toLowerCase(char str[]);

int main() {
    char str[100];
    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin);
    toLowerCase(str);
    printf("Lowercased: %s\n", str);
    return 0;
}

void toLowerCase(char str[]) {
    for (int i = 0; str[i] != '\0'; i++) {
        if (str[i] >= 'A' && str[i] <= 'Z') {
            str[i] += 32;
        }
    }
}

String Copy Operation

Develop a function that duplicates the contents of a source character array into a destination array.

#include <stdio.h>

void copyString(char destination[], const char source[]);

int main() {
    char source[100], destination[100];
    printf("Enter a string: ");
    fgets(source, sizeof(source), stdin);
    copyString(destination, source);
    printf("Copied: %s\n", destination);
    return 0;
}

void copyString(char destination[], const char source[]) {
    int i = 0;
    while (source[i] != '\0') {
        destination[i] = source[i];
        i++;
    }
    destination[i] = '\0';
}

Lexicographical String Comaprison

Construct a function to compare two strings lexicographically, returning 1 if the first is greater, -1 if smaller, and 0 if they are identical.

#include <stdio.h>

int compareStrings(const char s1[], const char s2[]);

int main() {
    char s1[100], s2[100];
    printf("Enter first string: ");
    fgets(s1, sizeof(s1), stdin);
    printf("Enter second string: ");
    fgets(s2, sizeof(s2), stdin);
    printf("Comparison result: %d\n", compareStrings(s1, s2));
    return 0;
}

int compareStrings(const char s1[], const char s2[]) {
    int i = 0;
    while (s1[i] != '\0' || s2[i] != '\0') {
        if (s1[i] > s2[i]) return 1;
        if (s1[i] < s2[i]) return -1;
        i++;
    }
    return 0;
}

Prime Factorization

Write a function that decomposes an integer into its prime factors and prints the result as a multiplication sequence, e.g., 12=2*2*3.

#include <stdio.h>

void factorize(int value);

int main() {
    int value;
    printf("Enter an integer: ");
    scanf("%d", &value);
    factorize(value);
    return 0;
}

void factorize(int value) {
    int original = value;
    printf("%d=", original);
    int is_first = 1;
    int divisor = 2;
    while (value > 1) {
        if (value % divisor == 0) {
            if (!is_first) printf("*");
            printf("%d", divisor);
            value /= divisor;
            is_first = 0;
        } else {
            divisor++;
        }
    }
    printf("\n");
}

Integer Digit Counter

Create a function that calculates the number of digits in an integer, properly handling negative values and zero.

#include <stdio.h>

int countDigits(int number);

int main() {
    int number;
    printf("Enter an integer: ");
    scanf("%d", &number);
    printf("Digit count: %d\n", countDigits(number));
    return 0;
}

int countDigits(int number) {
    if (number == 0) return 1;
    if (number < 0) number = -number;
    int digits = 0;
    while (number > 0) {
        number /= 10;
        digits++;
    }
    return digits;
}