The inequality of string constants and the copy of strings in C + +

#include <iostream>

void Main (void)
{
    if ("test" = = "Test")
    {
        cout<< "equal";
    }
    Else
    {
        cout<< "Not Equal";
    }
}

In the code above, we test that the two string constants for test are equal and, by common sense, should be equal, and that they will get the same conclusion in some procedural languages, but not in C + +.

Why, then?

The answer is here: Because string constants are stored in computer memory, the addresses of two string constants are not the same, so this comparison will naturally not get the results we need, if you want to make comparisons of equality should use STRCMP () the number of the Han to compare!

#include <iostream>
#include <string>
using namespace Std;

void Main (void)
{
    if (strcmp ("Test", "Test") ==0)
    {
        cout<< "equal";
    }
    Else
    {
        cout<< "Not Equal";
    }
    Cin.get ();
}

strcmp () is the prototype of the function, int strcmp (const char* str1,const char* str)

Quite will return an integer equal to 0, which will return a non-0 integer when not equal.

#include <iostream>
#include <string>
using namespace Std;
void Main (void)
{
    Char test[]= "Test str!";
    Char str[15];
    strcpy (str,test);
    cout<<str<<endl;

    int a[]={1,2,3,4,5};
    int b[5];
    memcpy (B,a,sizeof (a));
    for (int i=0;i<5;i++)
    {
        cout<<b[i]<< ",";
    }
    Cin.get ();
}

The strcpy in the above code is used to handle copy of the string Math group, because the string array belongs to the const char*, which is the constant pointer, so it is not possible to use a= "test str!"; , followed by the memcpy used to handle the copy processing of the array at the end of the memcpy, the third parameter is the amount of memory space required for B to be set in memory, and is processed with sizeof (a) *sizeof (int).