в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:30:28Z

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==copy constructor==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
#include <string>
using std::string;
int main()
{
string s1( "AA1234567890asdfasdf" );
string s2( " AAB" );
string s3;
// test copy constructor
string *s4Ptr = new string( s1 );
cout << "\n*s4Ptr = " << *s4Ptr << "\n\n";
return 0;
}</source>
<pre class=codeResult>*s4Ptr = AA1234567890asdfasdf</pre>

==Create a string from a vector<char>==

<source lang="cpp">#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
string strA("This is a test.");
// Create a string from a vector<char>.
vector<char> vec;
for(int i=0; i < 10; ++i)
vec.push_back("A"+i);
string strC(vec.begin(), vec.end());
cout << "Here is strC, which is constructed from a vector:\n";
cout << strC << endl;
return 0;
}</source>

==Create a string object using another string object==

<source lang="cpp">#include <iostream>
#include <string>
using namespace std;
int main()
{
string str1("A");
string str2("B");
string str3("G");
string str4;
cout << " str1: " << str1 << endl;
cout << " str2: " << str2 << endl;
cout << " str3: " << str3 << "\n\n";
// Create a string object using another string object.
cout << "Initialize str5 with the contents of str1.\n";
string str5(str1);
cout << "str5: " << str5 << "\n\n";
return 0;
}</source>

==Define a string variable, assign a value and display it==

<source lang="cpp">#include <iostream>
#include <string>
using namespace std ;
using std::cout;
using std::cin;
int main()
{
string s = "www.java2s.com \n";
cout <<s;
return 0;
}</source>
<pre class=codeResult>www.java2s.com</pre>

==Input from an istringstream object.==

<source lang="cpp">#include <iostream>
#include <string>
#include <sstream>
using namespace std;
main()
{
string input( "Input test 123 4.7 A" );
istringstream inputString( input );
string string1, string2;
int i;
double d;
char c;
inputString >> string1 >> string2 >> i >> d >> c;
cout << "The following items were extracted\n"
<< "from the istringstream object:"
<< "\nstring: " << string1
<< "\nstring: " << string2
<< "\n int: " << i
<< "\ndouble: " << d
<< "\n char: " << c;
// attempt to read from empty stream
long l;
if ( inputString >> l )
cout << "\n\nlong value is: " << l << endl;
else
cout << "\n\ninputString is empty" << endl;
return 0;
}</source>

==Loop through the string array==

<source lang="cpp">#include <iostream>
#include <list>
#include <algorithm>
#include <string>
using namespace std;
int main( ) {
string arrStr[5] = {"A", "B", "C", "D", "E"};
for (string* p = &arrStr[0]; p != &arrStr[5]; ++p) {
cout << *p << endl;
}
}</source>
<pre class=codeResult>A
B
C
D
E</pre>

==string basics==

<source lang="cpp">#include <iostream>
#include <string>
using namespace std;
int main()
{
string str1("Alpha");
string str2("Beta");
string str3("Omega");
string str4;
// assign a string
str4 = str1;
cout << str1 << "\n" << str3 << "\n";
// concatenate two strings
str4 = str1 + str2;
cout << str4 << "\n";
// concatenate a string with a C-string
str4 = str1 + " to " + str3;
cout << str4 << "\n";
// compare strings
if(str3 > str1) cout << "str3 > str1\n";
if(str3 == str1+str2)
cout << "str3 == str1+str2\n";
/* A string object can also be
assigned a normal string. */
str1 = "This is a null-terminated string.\n";
cout << str1;
// create a string object using another string object
string str5(str1);
cout << str5;
// input a string
cout << "Enter a string: ";
cin >> str5;
cout << str5;
return 0;
}</source>
<pre class=codeResult>Alpha
Omega
AlphaBeta
Alpha to Omega
str3 > str1
This is a null-terminated string.
This is a null-terminated string.
Enter a string: a string
a</pre>

==Using a dynamically allocated ostringstream object.==

<source lang="cpp">#include <iostream>
#include <string>
#include <sstream>
using namespace std;
main()
{
ostringstream outputString;
string s1( "Output of several data types " ),
s2( "to an ostringstream object:" ),
s3( "\n double: " ),
s4( "\n int: " ),
s5( "\naddress of int: " );
double d = 123.4567;
int i = 22;
outputString << s1 << s2 << s3 << d << s4 << i << s5 << &i;
cout << "outputString contains:\n" << outputString.str();
outputString << "\nmore characters added";
cout << "\n\nafter additional stream insertions,\n"
<< "outputString contains:\n" << outputString.str()
<< endl;
return 0;
}</source>

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