A truck trajectory is represented by a sequence of location points of the truck

Question

A truck trajectory is represented by a sequence of location points of the truck reported at different time. Her we show an example trajectory that consists of location points reported at a 30-second interval. Every locatio point (a line) has five columns, which represent the date (day/month/year), time (hour:minute:second), latitud longitude, and unique id (6 characters) of the location point, respectively 10/9/02 9:15:59 23.845089 38.018470 DXUYHu 10/9/02 9:16:29 23.845179 38.018069 tKoPTx 10/9/02 9:16:59 23.845530 38.018241 JPQbNb 10/9/02 9:17:29 23.845499 38.017440 aEWdXS 10/9/02 9:17:59 23.844780 38.015609 gqeEjx 10/9/02 9:18:29 23.844780 38.014018 aQArkX 10/9/02 9:18:59 23.844869 38.012569 fhQIAS 10/9/02 9:19:29 23.845360 38.011600 BhngfQ 10/9/02 9:19:59 23.845550 38.010650 rgwehm 10/9/02 9:20:29 23.845100 38.010478 jdBgpN For example, the first line of the sequence represents a location point reported at 9:15:59 on 10/9/02 with coordinate of (23.845089, 38.018470). This data point has a unique id of "DXUYHu"

Explanation / Answer

In all such problems where you have to parse some text data and then tokenize the line to extract few fields, use strtok() or strtok_r() functions. Following is a sample code to read, tokenize and fill the data into two separate arrays -

#include <stdio.h>

#include <string.h>

int main()

{

FILE *fp = fopen("data.dat", "r+");

char buf[256];

char *latitude[1024], *longitude[1024];

int i;

char *s;

if (fp == NULL) {

printf("file open failed ");

return -1;

}

while(!feof(fp)) {

// read the file line by line

memset(buf, 0, 256);

fgets(buf, 256, fp);

if (buf[0] == '') {

break;

}

printf("line: %s ", buf);

s = strtok(buf, " "); //returns the first token i.e the date

printf("str1: %s ", s);

s = strtok(NULL, " "); //returns the second token i.e the time

printf("str2: %s ", s);

s = strtok(NULL," "); // returns the third token i.e the latitude

// copy the string into newly allocated memory as the original memory belongs to buf

printf("str3: %s ", s);

latitude[i] = strdup(s);

s = strtok(NULL," "); // returns the fourth token i.e the longitude

printf("str4: %s ", s);

// copy the string into newly allocated memory as the original memory belongs to buf

longitude[i++] = strdup(s);

//continue and read the next line

}

int j;

for (j = i-1; j >=0; j--) {

printf("%s : %s ", latitude[j], longitude[j]);

}

}

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