Parse GPS String for Time and Coordinates

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

void parse_gprmc(char *nmea) {
  
     char field[7][20];   
    int field_index = 0, char_index = 0, i = 0;

    while (nmea[i] != '\0' && field_index < 7) {
        if (nmea[i] == ',') {
            field[field_index][char_index] = '\0'; 
            field_index++;
            char_index = 0;
        } else {
            if (char_index < 19)
                field[field_index][char_index++] = nmea[i];
        }
        i++;
    }
    field[field_index][char_index] = '\0';


    char time_str[9];
    time_str[0] = field[1][0];
    time_str[1] = field[1][1];
    time_str[2] = ':';
    time_str[3] = field[1][2];
    time_str[4] = field[1][3];
    time_str[5] = ':';
    time_str[6] = field[1][4];
    time_str[7] = field[1][5];
    time_str[8] = '\0';

    printf("Time: %s\n", time_str);
    printf("Latitude: %s %s\n", field[3], field[4]);
    printf("Longitude: %s %s\n", field[5], field[6]);
}

int main() {
    char nmea[100];
    fgets(nmea, sizeof(nmea), stdin);
    parse_gprmc(nmea);
    return 0;
}