我如何初始化动态分配的字符数组，所以我不会得到那些奇怪的字符？

Question

I want to use that array of characters in my game of "hangman" to view to tha user his current progress.

#include <iostream>
#include "randword.h"
#include <fstream>
#include <time.h>
#include <cstdlib>

using namespace std;



int main()
{
InitDictionary();
string tixaio=Randomword();
int m = tixaio.length();
int guesses=8;
char *charptr= new char[m];





for(int aa=0;aa<m;aa++){
charptr[aa]='-';

}

cout << "The word now looks like this: "<<charptr;


}

As soon as i try to cout<< charptr my array i got the usual "---------" plus some weird characters. How can i prevent those characters from showing up??

Answer 1

Strings in C and C++ must end in a "\\0" character: a character that is the value 0.

However, you should be using std::string instead of an array of characters. Then you won't have to worry about ending in a null character.

Answer 2

When you print an array of characters in C++, cout (or any ofstream object, for that matter) looks for the null terminating character to determine when to stop printing. Now, if you've only allocated m bytes for the array, and cout tries to access memory outside of those m bytes, you could possibly even get a segmentation fault.

One way to avoid this is to allocate space for one more character than what's needed, and assign '\\0' to that extra character.

char *charptr= new char[m+1];
charptr[m] = '\0';

Since you're using C++, it has a built in std::string class which you can use for your purpose. It automatically appends the null terminating character to the string. This behavior can be verified by calling the c_str() function on an object of type std::string (this converts std::string to char*). It'll always return n+1 characters, where n is the number returned by std::string's length() function. And as you can guess, the last character will be \\0.

Answer 3

它是一个char *，AFAIK，你需要在末尾有一个\\ 0终止符，以便打印知道何时停止。

Answer 4

clear the array to 0

memset (array, 0, size);

Or after you make the string, append a '\\0' just after the end of the string, which will indicate the end of string. This will prevent the printing routing go beyond the limit which you want. In your case you should place charptr[aa] = '\\0' just after the for loop. Make sure that you have enough allocated memory block to charptr you need to allocate the length of string + 1 (for the '\\0' character).

Answer 5

你必须在末尾插入'\\ 0'字符，因为它是一个以空字符结尾的字符串

Answer 6

You should add a \\0 as the last element after you fill up the array.

Better option is to use std:;string that is the C++ way of doing things better and in a elegant manner, without having to bother about null terminating as in case of char*