C++/String/string substr — различия между версиями
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Admin (обсуждение | вклад) м (1 версия: Импорт контента...) |
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Текущая версия на 10:25, 25 мая 2010
Содержание
Find substring day in a string and check if it was found
#include <string>
#include <iostream>
int main ()
{
using namespace std;
string strSample ("this is a test");
size_t nOffset = strSample.find ("test", 0);
// Check if the substring was found...
if (nOffset != string::npos)
cout << "found:" << nOffset;
else
cout << "not found." << endl;
return 0;
}
Obtain a substring
#include <iostream>
#include <string>
using namespace std;
int main()
{
string str1("this is a test");
cout << " str1: " << str1 << endl;
// Obtain a substring.
str1 = str1.substr(5, 4);
cout << str1 << "\n\n";
return 0;
}
Split file name in command line into base name and extension
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <string>
using namespace std;
int main (int argc, char* argv[])
{
string filename, basename, extname, tmpname;
const string suffix("tmp");
/* for each command-line argument
* (which is an ordinary C-string)
*/
for (int i=1; i<argc; ++i) {
// process argument as file name
filename = argv[i];
// search period in file name
string::size_type idx = filename.find(".");
if (idx == string::npos) {
// file name does not contain any period
tmpname = filename + "." + suffix;
}
else {
/* split file name into base name and extension
* - base name contains all characters before the period
* - extension contains all characters after the period
*/
basename = filename.substr(0, idx);
extname = filename.substr(idx+1);
if (extname.empty()) {
// contains period but no extension: append tmp
tmpname = filename;
tmpname += suffix;
}
else if (extname == suffix) {
// replace extension tmp with xxx
tmpname = filename;
tmpname.replace (idx+1, extname.size(), "xxx");
}
else {
// replace any extension with tmp
tmpname = filename;
tmpname.replace (idx+1, string::npos, suffix);
}
}
// print file name and temporary name
cout << filename << " => " << tmpname << endl;
}
}
string member function substr
#include <iostream>
using std::cout;
using std::endl;
#include <string>
using std::string;
int main()
{
string s1( "AA1234567890asdfasdf" );
string s2( " AAB" );
string s3;
// test string member function substr
cout << "The substring of s1 starting at location 0 for\n"
<< "14 characters, s1.substr(0, 14), is:\n"
<< s1.substr( 0, 14 ) << "\n\n";
return 0;
}
/*
The substring of s1 starting at location 0 for
14 characters, s1.substr(0, 14), is:
AA1234567890as
*/
substr "to-end-of-string" option
#include <iostream>
using std::cout;
using std::endl;
#include <string>
using std::string;
int main()
{
string s1( "AA1234567890asdfasdf" );
string s2( " AAB" );
string s3;
// test substr "to-end-of-string" option
cout << "The substring of s1 starting at\n"
<< "location 5, s1.substr(5), is:\n"
<< s1.substr( 5 ) << endl;
return 0;
}
/*
The substring of s1 starting at
location 5, s1.substr(5), is:
4567890asdfasdf
*/