Question

语言：C ++，编译器：MSVS（/ Za）和g ++（是的，它必须适用于两者），级别：初学者

我正在尝试从char *中删除数据，以便我可以重新分配它并继续我的程序。我创建一个新的char *，为它分配命令行参数的值，进行一些验证，然后如果验证失败，它应该解除分配char *并让我为var分配新数据但是我得到了一个“堆”腐败检测到“视觉工作室的错误。我对我当前代码的修复以及任何其他可以更清晰/更简洁地完成的方式感到好奇。

在main（）中：

//...
//make non constant versions to be messed with
char* ba = new char[ strlen(argv[4]) + 1 ];
char* num = new char[ strlen(argv[2]) + 1 ];

//make non constant versions of commandline stuff
nonConstant( argv[4], argv[2], ba, num );

//do the conversion and printing
convert( ba, num );
//...

转换是这样的：

//...
if( error ) {
    getNew(ba, num, &error);
}
//...

这里是getNew：

void getNew( char* ba, char* num, bool error ) {

//if there's an error in their numbers let them input new stuff and check to see if that's valid
while( error ) {
    //tell the user that the input was bad an prompt for more, use getline because strings are weird
    //cin stuff here (this part works, no problems)

    //free up base and num so I can reassign them
    delete[] ba; //<--this line fails
    delete[] num;

    //set lengths = to lengths of input + 1 for \0
    ba = new char[ inputBa.length() + 1 ];
    num = new char[ inputNum.length() + 1 ];

    //do the assignment of new input back to base and num
    inputBa.copy( ba, inputBa.length(), 0 );
    inputNum.copy( num, inputNum.length(), 0 );

    //ensure that the input was good this time
    validateInput( ba, num, error );
}

Answer 1

<强>停止！立即切换到std::string。

这将修复您的代码，并根据要求更加清晰/简洁。

Answer 2

如果您的getNew函数看起来可以重新分配本地ba和num所指向的内存，即delete[]它和new[]它。

但是ba中来电者num和convert呢？另外，ba中的num和main呢？它们按值传递给getNew，这意味着它们保持不变。他们继续指向他们原来的（现在死的）记忆位置。我猜你会继续在ba和num中使用那些现在毫无意义的convert和main值，直到它们导致崩溃。例如，如果您再次使用这些旧指针值调用getNew，getNew可能会在delete[]失败。

此外，还不能立即清楚error中convert的内容。当&error实际需要getNew参数时，为什么要将它作为bool（可能是指针）传递？它会编译，但无论如何它看起来都是一个问题。

Answer 3

通过char *＆amp;传递参数将解决问题。

#include <stdio.h>
#include <string.h>

void reassgnReference( char * &ba, char * &num );
void reassgnPointerToPointer( char ** ba, char ** num );

int main( int argc, char ** argv )
{
    if ( argc > 4 )
    {
        char * ba = new char[strlen( argv[ 4 ] ) + 1];
        char * num = new char[strlen( argv[ 2 ] ) + 1];

        strncpy( ba, argv[ 4 ], strlen( argv[ 4 ] ) );
        strncpy( num, argv[ 2 ], strlen( argv[ 2 ] ) );

        printf( "In the beginning, ba = %s, num = %s\n", ba, num );

        reassgnReference( ba, num );
        printf( "reassgnReference(), ba = %s, num = %s\n", ba, num );

        reassgnPointerToPointer( &ba, &num );
        printf( "reassgnPointerToPointer(), ba = %s, num = %s\n", ba, num );
}
else
{
    printf( "%s Expects at least 4 arguments\n", argv[ 0 ] );
}

return( 0 );
}

void reassgnReference( char *& ba, char *& num )
{
    delete[] ba;
    delete[] num;

    char const * const newBa = "ba from reference";
    char const * const newNum = "num from reference";

    ba = new char[strlen( newBa ) + 1];
    num = new char[strlen( newNum ) + 1];

    strncpy( ba, newBa, strlen( newBa ) );
    strncpy( num, newNum, strlen( newNum ) );
}

void reassgnPointerToPointer( char ** ba, char ** num )
{ 
    delete[] *ba;
    delete[] *num;

    char const * const newBa = "ba from pointer to pointer";
    char const * const newNum = "num from pointer to pointer";

    *ba = new char[strlen( newBa ) + 1];
    *num = new char[strlen( newNum ) + 1];

    strncpy( *ba, newBa, strlen( newBa ) );
    strncpy( *num, newNum, strlen( newNum ) );
}

C ++无法删除char *，不断破坏堆

3 个答案: