ptrstr.cpp

来自「C++ Primer Plus（第五版）第4章例题代码」· C++ 代码 · 共 34 行

// ptrstr.cpp -- using pointers to strings
#include <iostream>
#include <cstring>              // declare strlen(), strcpy()
int main()
{
    using namespace std;
    char animal[20] = "bear";   // animal holds bear
    const char * bird = "wren"; // bird holds address of string
    char * ps;                  // uninitialized

    cout << animal << " and ";  // display bear
    cout << bird << "\n";       // display wren
    cout << ps << "\n";     //may display garbage, may cause a crash

    cout << "Enter a kind of animal: ";
    cin >> animal;              // ok if input < 20 chars
    // cin >> ps; Too horrible a blunder to try; ps doesn't
    //            point to allocated space

    ps = animal;                // set ps to point to string
    cout << ps << "s!\n";       // ok, same as using animal
    cout << "Before using strcpy():\n";
    cout << animal << " at " << (int *) animal << endl;
    cout << ps << " at " << (int *) ps << endl;

    ps = new char[strlen(animal) + 1];  // get new storage
    strcpy(ps, animal);         // copy string to new storage
    cout << "After using strcpy():\n";
    cout << animal << " at " << (int *) animal << endl;
    cout << ps << " at " << (int *) ps << endl;
    delete [] ps;
    return 0; 
}