将字符串转换为double或float以执行数学公式

Question

I have a function that I am trying to convert from PHP. I am executing the function like this example:

latlong_hex("1234.5678N");

and I need the result to be processed but I am running into problems with the string to double conversion and the calculations. After the conversion, I am losing all numbers after the decimal. The HEX function at the bottom is working fine.

int latlong_hex(char* gps_coord)
{
    int gps_result;
    char direction[2] = {0};
    char gps_latlong[10] = {0};
    double latdeg;
    double tempDec;
    char* tempGPS;

    strncpy(gps_latlong, gps_coord, 9);
    strncpy(direction, gps_coord+9, 1);

    tempDec = strtod(gps_latlong, NULL);
    free(gps_latlong);

    tempDec = tempDec / 100;

    if(direction == 'W' || direction == 'S')latdeg = round((floor(tempDec)+((tempDec - floor(tempDec))/60),7))*-1;
    else latdeg = round((floor(tempDec) + ((tempDec - floor(tempDec))/60),7));
    if(latdeg > 0){
        gps_result = latdeg / 0.0000001;
    }
    else{
        gps_result = (4294967295 + (latdeg/0.0000001))  ;
    }

    dec_hex(gps_result);

    return 1;
}

Answer 1

This:

free(gps_latlong);

is instant undefined behavior, since gps_latlong is not a heap-allocated object. Remove that line.

Also, you should call strtod() directly on gps_coord , the local copying serves no purpose.