Extract data between two delimiters

问题

I just want to know whether it is possible to pick up the data that is present between two delimiters (delimiter being a string).

For example the original string is as under

<message%20type%3D"info"%20code%3D"20005">%20<text>Conference%20successfully%20modified</text>%20<data>0117246</data>%20%20</message>%20

and I want the data that is present between <text> tags. The string from which i need the data can be different. The string can also be like this

<message%20type%3D"info"%20code%3D"20001">%20<text>Conference%20deleted</text%20%20<vanity>0116976</vanity>%20</message>%20<message%20type%3D"info"%20code%3D"20002">%20<text>Number%20of%20conferences%20deleted</text>%20<data>1</data>%20%20</message>%20

but I always need the data present between the <text> tags.

So is it possible in C language or is there any alternative?

回答1:

I'd go with strstr().

For example:

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

int main(void) {
    char data[] = "<message%20type%3D\"info\"%20code"
                  "%3D\"20005\">%20<text>Conference%"
                  "20successfully%20modified</text>%"
                  "20<data>0117246</data>%20%20</mes"
                  "sage>%20";
    char *p1, *p2;
    p1 = strstr(data, "<text>");
    if (p1) {
        p2 = strstr(p1, "</text>");
        if (p2) printf("%.*s\n", p2 - p1 - 6, p1 + 6);
    }
    return 0;
}

回答2:

There are functions strtok() and strtok_r() which can be used to extract the data based on the delimiters.

char a[100] = "%20Conference%20successfully%20modified%200117246%20%20%20";
char *p = strtok(a,"%");
while(p != NULL)
{
  // Save the value in pointer p
  p = strtok(NULL,"%");
}

If you want the string a to be unmodified then have a separate array b char b[100] and copy the string to b

strcpy(b,a);

Code and output:

#include <stdio.h>

int main(void) {
    char a[100] = "%20Conference%20successfully%20modified%200117246%20%20%20";
    char *p = strtok(a,"%");
    char n[20];
    while(p != NULL)
    {
      strcpy(n,p);
      p = strtok(NULL,"%");
      printf("%s\n",n);
    }
    return 0;
}

Output:

20Conference
20successfully
20modified
200117246
20
20
20

PS: strtok() modifies the passed string.Check man http://linux.die.net/man/3/strtok_r

来源：https://stackoverflow.com/questions/28451377/extract-data-between-two-delimiters

标签

delimiter

string-parsing