C++ Tutorial/string/string search
Содержание
Search a null-terminated string: determine if url and url2 contain .com, .net, or .org.
<source lang="cpp">#include <iostream>
- include <cstring>
using namespace std; int main() {
const char *url = "server.com";
const char *url2 = "Apache.org";
const char *emailaddr = "Herb@server.com";
const char *tld[] = { ".com", ".net", ".org" };
const char *p;
// determine if url and url2 contain .com, .net, or .org.
for(int i=0; i < 3; i++) {
p = strstr(url, tld[i]);
if(p) cout << url << " has top-level domain " << tld[i] << endl;
p = strstr(url2, tld[i]);
if(p) cout << url2 << " has top-level domain " << tld[i] << endl;
}
return 0;
}</source>
Search for any of a set of characters. In this case, find the first @ or period.
<source lang="cpp">#include <iostream>
- include <cstring>
using namespace std; int main() {
const char *url = "server.com";
const char *url2 = "Apache.org";
const char *emailaddr = "Herb@server.com";
const char *tld[] = { ".com", ".net", ".org" };
const char *p;
// Search for any of a set of characters. In this case, find the first @ or period.
p = strpbrk(emailaddr, "@.");
if(p) cout << "Found " << *p << endl;
return 0;
}</source>
Search for a specific character
<source lang="cpp">#include <iostream>
- include <cstring>
using namespace std; int main() {
const char *url = "server.com";
const char *url2 = "Apache.org";
const char *emailaddr = "Herb@server.com";
const char *tld[] = { ".com", ".net", ".org" };
const char *p;
// Search for a specific character.
p = strchr(emailaddr, "@");
if(p) cout << "Site name of e-mail address is: " << p+1 << endl;
return 0;
}</source>
string search with custom comparison function
<source lang="cpp">/* 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 <string>
- include <iostream>
- include <algorithm>
using namespace std; bool nocase_compare (char c1, char c2) {
return toupper(c1) == toupper(c2);
} int main() {
string s1("This is a string");
string s2("STRING");
// compare case insensitive
if (s1.size() == s2.size() && // ensure same sizes
equal (s1.begin(),s1.end(), // first source string
s2.begin(), // second source string
nocase_compare)) { // comparison criterion
cout << "the strings are equal" << endl;
}
else {
cout << "the strings are not equal" << endl;
}
// search case insensitive
string::iterator pos;
pos = search (s1.begin(),s1.end(), // source string in which to search
s2.begin(),s2.end(), // substring to search
nocase_compare); // comparison criterion
if (pos == s1.end()) {
cout << "s2 is not a substring of s1" << endl;
}
else {
cout << """ << s2 << "\" is a substring of \""
<< s1 << "\" (at index " << pos - s1.begin() << ")"
<< endl;
}
}</source>
the strings are not equal "STRING" is a substring of "This is a string" (at index 10)
