atoi() 由于特殊字符而不转换整个字符串

Question

I have data in my.txt file containing different time ins and time outs of employees. For example, 10:20 but I initially designed the structure to have their data types to be of char arrays or string. Since I'll be using the time values in another function, I have to use the atoi() function to convert them into integer values. Problem is, there is a colon : in each of the time values. Would it be possible to convert the string 10:20 to an integer using atoi() so that I can it in my future functions? Does the use of atoi() allow some splitting or some sort so that I can convert my time value from string to int?

I tried

char time[10] = "10:20";

int val;

printf("string val = %s, int value = %d", time, atoi(time));

But my output is only string val = 10:20, int value = 10 so only the string before the : is read and converted to string. I would want that after converting, I would stil have 10:20 as the result but in integer because I am going to use relational operators with it.

Answer 1

It's not clear what you actually want, but maybe something like:

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

int
main(int argc, char **argv)
{
        char *time = argc > 1 ? argv[1] : "10:20";
        int d;
        char *e;

        d = strtol(time, &e, 10);
        if( *e == ':' ){
                d *= 100;
                d += strtol(e + 1, &e, 10);
        }
        if( *e != '\0' ){
                fprintf(stderr, "invalid input\n");
                return 1;
        }

        printf("string val = %s, int value = %d\n", time, d);
        return 0;
}

This will produce d = 1020 for the string "10:20". It's not at all clear to me what integer you want to produce, but that seems to be what you're looking for.

Answer 2

You can also use sscanf :

#include <stdio.h>

int main() {
  char const* time = "10:20";

  int h, m;
  if (sscanf(time, "%d:%d", &h, &m) != 2)
    return 1;

  printf("string val = %s, int value = %d\n", time, h * 100 + m);
}