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string substr ( size_t pos = 0, size_t n = npos ) const;
Generate substring
Returns a string object with its contents initialized to a substring of the current object.
This substring is the character sequence that starts at character position pos and has a length of n characters.
Parameters
- pos
- Position of a character in the current string object to be used as starting character for the substring.
If the position passed is past the end of the string, an out_of_range exception is thrown.
- n
- Length of the substring.
If this value would make the substring to span past the end of the current string content, only those characters until the end of the string are used.
npos is a static member constant value with the greatest possible value for an element of type size_t, therefore, when this value is used, all the characters between pos and the end of the string are used as the initialization substring.
Return Value
A string object containing a substring of the current object.
Example
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// string::substr
#include <iostream>
#include <string>
using namespace std;
int main ()
{
string str="We think in generalities, but we live in details.";
// quoting Alfred N. Whitehead
string str2, str3;
size_t pos;
str2 = str.substr (12,12); // "generalities"
pos = str.find("live"); // position of "live" in str
str3 = str.substr (pos); // get from "live" to the end
cout << str2 << ' ' << str3 << endl;
return 0;
}
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generalities live in details. |
Basic template member declarations
( basic_string<charT,traits,Allocator> )
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typedef typename Allocator::size_type size_type;
basic_string substr (size_type pos =0, size_type n=npos) const;
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See also
| string::find | Find content in string (public member function) |
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