convert multiple lines to binary in c

Question

I am trying to read in multiple lines in a file ,convert each line to binary. I reckon that for each line, we need to shift every 4 char in order to store the next 4. However I am not sure if the only way to store binary i.e. 0010 is as a String.Can someone please help? I can't get my head around how to do this. Many thanks!

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    int n, k;
    char * nptr = "1e2", *endptr;              // nptr contains hex
    n = strtol(nptr, &endptr, 16);             // n contains decimal
    char bin[33];                              // bin contains binary
    int index = 0;
    while(n != 0)
    {
        if (n & 1)
            bin[index++] = '1';
        else
            bin[index++] = '0';
        n = n >> 1;
    }
    bin[index] ='\0';
    printf("%s", strrev(bin));
    return 0;
}

edit:
if you want a 32 bit number with leading zeros then:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    int n, c, k;
    char * nptr = "1e2", *endptr;              // nptr contains hex
    n = strtol(nptr, &endptr, 16);
    char bin[33];
    int index = 0;
    for (c = 31; c >= 0; c--)
    {
        k = n >> c;
        if (k & 1)
            bin[index++] = '1';
        else
            bin[index++] = '0';
    }
    bin[index] = '\0';
    printf("%s", bin);
    return 0;
}

Answer 2

This accepts a three character hex input and outputs a 12 character binary string. The function will accept arguments to change the input and output lengths. iLenOut should be at least the length of the hex input * 4.

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

int hextobin ( char *pacHexIn, char *pacBinOut, int iLenOut) {
    char acHexChars[17] = { "0123456789abcdef"};
    char *pcEachHex = NULL;
    unsigned int  uiHexIndex = 0;
    int  iEachBit = 0;
    int  iInputLen = 0;
    int  iOutputLen = iLenOut;

    if ( iLenOut % 4) {
        printf ( "as each hex character will result in 4 bits, use an even multiple of 4\n");
        return 2;
    }
    while ( iOutputLen) {
        pacBinOut[iOutputLen] = '0';
        iOutputLen--;
    }
    iOutputLen = iLenOut;
    iInputLen = strlen ( pacHexIn); // get length of input
    while ( iInputLen > 0) {
        iInputLen--;
        iOutputLen -= 4;
        pacHexIn[iInputLen] = tolower( pacHexIn[iInputLen]); // make sure input is lower case
        if ( ( pcEachHex = strchr ( acHexChars, pacHexIn[iInputLen])) != NULL) { // get index to acHexChars
            uiHexIndex = pcEachHex - acHexChars; // difference will be the value of the hex char f=15...

            for ( iEachBit = 3; iEachBit >= 0; iEachBit--) { // loop through the bits
                if ( 1 & ( uiHexIndex >> iEachBit)) { // right shift and compare to 1
                    pacBinOut[ iOutputLen + ( 3 - iEachBit)] = '1'; // set to 1
                }
                else {
                    pacBinOut[ iOutputLen + ( 3 - iEachBit)] = '0'; // set to 0
                }
            }
        }
        else {
            printf ( "Only input hex values 0-9 and a-f\n"); // invalid input
            return 1;
        }
    }
    pacBinOut[iLenOut] = '\0'; // make sure string is terminated
    return 0;
}

int main()
{
    char acInput[9] = { 0};
    char acBinary[33] = { "00000000000000000000000000000000"};
    scanf ( "%3s", acInput); // input 3 hex characters, acInput will allow for up to 8 characters
    if ( ( hextobin ( acInput, acBinary, 12)) == 0) { // return binary string of 12 characters, acBinary will allow up to 32
        printf ( "%s\n", acBinary); // print result
    }
    else {
        printf ( "conversion failed\n");
    }
    return 0;
}

Answer 3

Try this:

char inter[5];

const char *binary = std::bitset<4>(input [i] -'0').to_string().c_str(); //to binary
strcpy(inter, binary);

need to include <bitset>, <string> and <string.h>

Answer 4

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

int main(int argc, char *argv[]){
    static const char *table[] = {
        "0000","0001","0010", "0011",
        "0100","0101","0110", "0111",
        "1000","1001","1010", "1011",
        "1100","1101","1110", "1111"
    };
    FILE *file = fopen("data.txt", "r");
    char input[5], output[13] = {0};

    while (fgets(input, 5, file)!=NULL){
        char *p = output;
        for ( int i = 0; i < 3; ++i){
            if(isdigit(input[i]))
                memcpy(p, table[input[i]-'0'], 4);
            else //a-f
                memcpy(p, table[tolower(input[i])-'a'+10], 4);
            p += 4;
        }
        puts(output);
    }
    fclose(file);
    return 0;
}