String data types in C + +

1, string

The initialization of string, in C + +, A string is a data type;

(1), initialization of string, traversal, string connection

The code is as Follows:

#include <iostream> #include <string> #include <stdio.h>using namespace std;int  Main (void) {  //string initialization, in C + + The string is a data type;    string s1 =  " ABCDEFG ";     string s2 (" abcdefg ");     string s3 (s2);     string s4 = s1;  //call Copy constructor;     string s5 ( 10,  ' A '); the characters in THE//10 space are ' a ';     s5 = s1;     cout << "s3:" <<s3<<endl;    cout<< "s5:" <<s5<<endl;// The traversal of string, overloading the [] operator,     //1, array Way traversal []    for (int i = 0;  i < s1.length ();  i++) {        cout<<s1[i ]<< " ",   //error (subscript out of bounds), will not be out of the exception, causing the program interruption;    }        cout<<endl;    //2, iterators     string::iterator it;      for (it = s1.begin ();  it != s1.end ();  it++) {         cout<<*it<< " ";    }    cout< <endl;    //3, function at () Traverse     for (int i = 0; i  < s1.length ();  i++) {        cout<<s1.at (i) << " ";  //will cut out abnormal, reasonable to solve the subscript out of bounds;     }    cout<<endl;// Character pointer and string conversion     //at this point, s1====>char *  the first address of the memory to reveal;     printf ("s1:%s \n",  s1.c_str ()),     //s1 content copied to buf;     char  buf[123] = {0};    s1.copy (buf, 2, 0);//n, pos; Subscript starting from 0 copy 2 characters to buf, will not be c-style, Note yourself plus 0 end sign; The connection     s1 = s1 + of the    cout<<buf<<endl;//string substring  s2; //direct + table: string connection;     s1 += s2; //+= is also a string connection;     s1.append (s4);  //call method Append () is also a string connection;    cout<<s1<<endl;            return 0;}

Operation Result:

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(2), string lookup, Replace

The code is as Follows:

#include <iostream> #include <string> #include <string.h>using namespace std;int  Main (void) {//string Find and replace     string s1 =  ' wbm hello wbm 111  wbm 222 wbm 333 ";     //1, First appearance wbm subscript     int  Index = s1.find ("wbm",  0);     cout<< "index :" <<index <<endl;    //2, WBM Each occurrence of the array subscript     /*  int offindex  = s1.find ("wbm",  0);     while (offindex != -1) {         cout<< "offindex :" <<offindex<<endl;         offindex += strlen ("wbm");         offindex = s1.find ("wbm",  offindex);     }*/    // 3. Replace the lowercase WBM with uppercase &NBSP;&NBSp;  int offindex = s1.find ("wbm",  0);      while ( Offindex != -1) {        cout<< "offindex :" < <offindex<<endl;        s1.replace (offindex, strlen ("WBM "), " WBM ")  //start with subscript offindex, remove n characters, Replace with the following characters;         offindex  += strlen ("wbm");         offindex = s1.find ("wbm") ,  offindex);    }    cout<< "s1:" <<s1<<endl;     string s3 =  "aaa bbb ccc";     s3.replace ( 0, 3,  "AAA");   //replacement function;    cout<< "s3:" <<s3<<endl;     return 0;}

Operation Result:

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(3), deletion and insertion of intervals

The code is as Follows:

#include <iostream> #include <string> #include <algorithm>using namespace std;int  Main (void) {//interval Delete and insert     string s1 =  ' hello1 hello2 hell03 ';     string::iterator it = find (s1.begin (),  s1.end (),  ' l ');     if (it != s1.end ()) {        s1.erase (it);  // Delete algorithm;    }       cout<< "s1 :" <<s1< <endl;    s1.erase (s1.begin (),  s1.end ())  //delete n characters starting from pos;     cout<< "s1 Delete all:" <<s1<<endl;    cout<< "s1 length:" << S1.length () <<endl;    string s2 =  "BBB";     S2.insert (0,  "AAA"),   //head interpolation     s2.insert (s2.length (),  "CCC");//tail Insertion method     cout<<s2<<endl;    return 0;} 

Operation Result:

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(4), case of String conversion----function pointer

The code is as Follows:

#include <iostream> #include <string> #include <algorithm>using namespace Std;int main (void) {string    S1 = "aaabbb";    Transform (s1.begin (), s1.end (), s1.begin (), 0, Toupper);//toupper can be: entry address of function, function object, cout<<s1<<endl;    String s2 = "aaabbb";    Transform (s2.begin (), s2.end (), s2.begin (), 0, tolower);    cout<<s2<<endl; Return 0;}

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String data types in C + +