get substring from C string in C++

Question

I have C string

   char s[] = "n1=1&n2=2&name=test&sername=test2";

I need to take from the string value name, ie, "test" and written in a separate variable.

So I need to find the value between "&name=" and the next &

So you'd use strlen() to find an end iterator, std::search() to find the position of the where the parameter starts, and std::find() where it ends. What part exactly is your problem? — Dietmar Kühl
– Dietmar Kühl, Commented Nov 29, 2015 at 20:02
As a generic solution, you could first split on & to get the collection of pairs (a=b), then split on = to get a key and value for each pair. — Grigorii Chudnov
– Grigorii Chudnov, Commented Nov 29, 2015 at 22:39

villasv · Accepted Answer · 2015-11-29 20:10:21Z

5

Because you tagged this as C++ I'll use std::string instead:

char s[] = "n1=1&n2=2&name=test&sername=test2";
string str(s);
string slice = str.substr(str.find("name=") + 5);

string name = slice.substr(0, slice.find("&"));

You could also do this with regex and capture all those values at once, also saving the time of creating a string.

char s[] = "n1=1&n2=2&name=test&sername=test2";

std::regex e ("n1=(.*)&n2=(.*)&name=(.*)&sername=(.*)");
std::cmatch cm;
std::regex_match(s,cm,e);

cout << cm[3] << endl;

edited Nov 29, 2015 at 20:10

answered Nov 29, 2015 at 20:04

villasv

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1 Comment

Nastya Gorobets Over a year ago

Thanks.It is that I need.

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