Get specific portion of text from string in C

Question

For a program I am working on I need to get info from a specific area from an online xml document. Right now I have save the xml as a string and then use press=xml.substr(1906,5); to get what I need from it. This is one line I pull info from: <pressure_in>30.17</pressure_in> The problem with this is that if the value between is longer than the specified length, (5 characters in this case) I cant get the desired value. How could I get it reliably?

[Use a real XML parser?](http://stackoverflow.com/questions/9387610/what-xml-parser-should-i-use-in-c) — WhozCraig, Dec 02 '13 at 01:02
If you're able to get that line without an full blown XML parser, just use a simple regular expression. — turnt, Dec 02 '13 at 01:06

score 1 · Answer 1 · answered Dec 02 '13 at 01:02

1

First convert the string to an xml structure, then extract what you need with an XPath selector. A very simple example can be found here:

http://xmlsoft.org/tutorial/apd.html

answered Dec 02 '13 at 01:02

peterh

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score 1 · Accepted Answer · answered Dec 02 '13 at 05:30

Have you considered something like this:

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

int main ()
{
    // sample string below:
    char* xmlText = "<pressure_in>30.17134</pressure_in>";
    int n = strlen(xmlText);
    for (int i = 0; i<n; i++) {
        if (isdigit(xmlText[i]) || xmlText[i] == '.') {
            // store result or just print:
            printf("%c",xmlText[i]);
        }
    }
    printf("\n")
    return 0;
}

Output:

30.17134

Thanks, this helped me figure out what to do. – Cameron346 Dec 02 '13 at 21:41 — Cameron346, Dec 02 '13 at 21:41

Get specific portion of text from string in C

2 Answers2