Number System Conversion In C (Assignment)

NSC.c

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

int from, number, to;
long long binNumber;
char hexNum[100], binNum[100];
char options[5][100] = {" ", "Decimal", "Hexadecimal", "Octal", "Binary"};

void selectOption() {
    for (int i=1; i<5; i++) {
        printf("%d. %s \n", i, options[i]);
    }
}


void errorMessage() {
    printf("Something is wrong :( !!!");
}


int hexadecimalToBinary(char hexVal[]) {
    char hexDigitToBinary[16][100] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};
    char hexDigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    int i = 0, j;

    for(i=0; hexVal[i] != '\0'; i++)  {
        for(j=0; j<16; j++){
          if(hexDigits[j] == hexVal[i]){
                strcat(binNum, hexDigitToBinary[j]);
            }
        }
    }
    return atoi(binNum);
}


long int binaryToOctal(int binarynum) {

    long int octalnum = 0, j = 1, remainder;

    while (binarynum != 0) {
        remainder = binarynum % 10;
        octalnum = octalnum + remainder * j;
        j = j * 2;
        binarynum = binarynum / 10;
    }

    return octalnum;
}


void binaryToHexadecimal(long long binary) {
    int hexConstant[] = {0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111};
    long long tempBinary;
    char hex[20];
    int index, i, digit;

    tempBinary = binary;
    index = 0;

    while(tempBinary!=0) {
        digit = tempBinary % 10000;
        for(i=0; i<16; i++) {
            if(hexConstant[i] == digit) {
                if(i<10) {
                    hex[index] = (char)(i + 48);
                } else {
                    hex[index] = (char)((i-10) + 65);
                }
                index++;
                break;
            }
        }
        tempBinary /= 10000;
    }
    hex[index] = '\0';
    strrev(hex);
    printf("%s", hex);
}


long long octalToBinary(int number) {

    int octaVal[] = {0, 1, 10, 11, 100, 101, 110, 111};
    long long binary=0, place=1;
    int rem;

    while(number > 0) {
        rem = number % 10;
        binary = (octaVal[rem] * place) + binary;
        number /= 10;
        place *= 1000;
    }
    return binary;
}


void decimalTo(int number, int to) {
    int binaryNum[32], octalNum[100], i = 0;
    char hexaDeciNum[100];

    switch (to) {
        case 1:
            printf("Gotchya, %d\n", number);
            break;

        case 2:
            while (number != 0) {
                int temp  = 0;
                temp = number % 16;
                if(temp < 10) {
                    hexaDeciNum[i] = temp + 48;
                    i++;
                } else {
                    hexaDeciNum[i] = temp + 55;
                    i++;
                }
                number /= 16;
            }
            for(int j=i-1; j>=0; j--)
                printf("%c", hexaDeciNum[j]);
            break;

        case 3:
            while (number != 0) {
                octalNum[i] = number % 8;
                number /= 8;
                i++;
            }
            for (int j = i-1; j >= 0; j--)
                printf("%d", octalNum[j]);
            break;

        case 4:
            while (number > 0) {
                binaryNum[i] = number % 2;
                number /= 2;
                i++;
            }
            for (int j = i-1; j >= 0; j--)
                printf("%d", binaryNum[j]);
            break;

        default:
            errorMessage();
    }
}


void hexadecimalTo(char hexNum[], int to) {
    int len = strlen(hexNum), base = 1, dec_val = 0, x;
    switch (to) {
        case 1:
            for (int i=len-1; i>=0; i--) {
                if (hexNum[i]>='0' && hexNum[i]<='9') {
                    dec_val += (hexNum[i] - 48)*base;
                    base = base * 16;
                } else if (hexNum[i]>='A' && hexNum[i]<='F') {
                    dec_val += (hexNum[i] - 55)*base;
                    base = base*16;
                }
            }
            printf("%d", dec_val);
            break;

        case 2:
            printf("Gotchya, %s\n", hexNum);
            break;

        case 3:
            x = hexadecimalToBinary(hexNum);
            printf("%lo", binaryToOctal(x));
            break;

        case 4:
            printf("%d", hexadecimalToBinary(hexNum));
            break;

        default:
            errorMessage();
    }
}


void octalTo(int number, int to) {
    int dec_value = 0, base = 1, temp = number;
    long long x = octalToBinary(number);
    switch (to) {
        case 1:
            while (temp) {
                int last_digit = temp % 10;
                temp /= 10;
                dec_value += last_digit * base;

                base *= 8;
            }
            printf("%d", dec_value);
            break;

        case 2:
            binaryToHexadecimal(x);
            break;
        case 3:
            printf("Gotchya, %d\n", number);
            break;

        case 4:
            printf("%lld", octalToBinary(number));
            break;

        default:
            errorMessage();
    }
}


void binaryTo(long long number, int to) {
    int  num, decimal_val = 0, base = 1, rem;

    switch (to) {
        case 1:
            while (number > 0) {
                rem = number % 10;
                decimal_val += rem * base;
                number /= 10;
                base *= 2;
            }
            printf("%d", decimal_val);
            break;

        case 2:
            binaryToHexadecimal(number);
            break;

        case 3:
            printf("%lo", binaryToOctal(number));
            break;

        case 4:
            printf("Gotchya, %d\n", number);
            break;

        default:
            errorMessage();
    }
}


void operation() {
    printf("\nSelect an option to convert your number \"to\" - \n");
    selectOption();
    printf(">>> ");
    scanf("%d", &to);
}


int main() {
    printf("------------------------------------------");
    printf("\n### Number System Conversion by Soley! ###\n");
    printf(">> To exit the program, use : CTRL + C <<\n");
    printf("------------------------------------------\n\n");

    do {
        printf("Select an option to convert your number \"from\" - \n");
        selectOption();
        printf(">>> ");
        scanf("%d", &from);

        switch(from) {
            case 1:
                printf("\nEnter the number you want to convert: ");
                scanf("%d", &number);
                operation();
                decimalTo(number, to);
                break;

            case 2:
                printf("\nEnter the number you want to convert: ");
                scanf("%s", &hexNum);
                operation();
                hexadecimalTo(hexNum, to);
                break;

            case 3:
                printf("\nEnter the number you want to convert: ");
                scanf("%d", &number);
                operation();
                octalTo(number, to);
                break;

            case 4:
                printf("\nEnter the number you want to convert: ");
                scanf("%lld", &binNumber);
                operation();
                binaryTo(binNumber, to);
                break;

            default:
                errorMessage();
        }

        printf("\n\n");

    } while(1);

    return 0;
}