传递从vector获得的数组指针时使用EXC_BAD_ACCESS

C++: EXC_BAD_ACCESS when passing array pointer obtained from vector

本文关键字：EXC BAD 指针 ACCESS 数组 vector      更新时间：2023-10-16

编辑:我明白了。当deflateReadOut()实例化数组时，由于数组太大而无法放在堆栈中，因此在调用它时抛出EXC_BAD_ACCESS错误。有用的链接:链接

这个EXC_BAD_ACCESS错误把我难住了。到目前为止，我的程序所做的是创建一个包含四个大型无符号字符数组的二维向量数组，用100填充位置0的数组，并尝试传递指向该数组的指针，其中包含所有100。但是，当它到达函数调用时，发生EXC_BAD_ACCESS错误。我通过打印检查了数组的完整性，它打印得很好。下面的代码。

#include <stdint.h>
#include <map>
#include <stdio.h>
#include <iostream>
#include <time.h>
#include <string.h>
#include <assert.h>
#include <cstdlib>
#include <sstream>
#include <zlib.h>
#include "Hash.h"
#define CHUNK 16777216
using namespace std;
class WSUMap {
public:
    vector<vector <unsigned char> > chunk;
    int xComp[4];
    int yComp[4];
    vector<int> priority;
    Hash hashChunk;
    WSUMap() {
        chunk.reserve(4);
        chunk[0] = vector<unsigned char>(CHUNK);
        chunk[1] = vector<unsigned char>(CHUNK);
        chunk[2] = vector<unsigned char>(CHUNK);
        chunk[3] = vector<unsigned char>(CHUNK);
        priority.push_back(0);
        priority.push_back(1);
        priority.push_back(2);
        priority.push_back(3);
        xComp[0] = -1;
        xComp[1] = -1;
        xComp[2] = -1;
        xComp[3] = -1;
        yComp[0] = -1;
        yComp[1] = -1;
        yComp[2] = -1;
        yComp[3] = -1;
    }
    //Important part starts here:
    void generate() {
        for (int i = 0; i<CHUNK; i++) {
            chunk[0][i]=100;
        }
        for (int i = 0; i < 16; i++) {
            for (int j = 0; j < 16; j++) {
                cout << chunk[0][0] << endl;
                unsigned char* ch = &chunk[0][0];
                cout << ch[0] << endl;
                deflateReadOut(i, j, ch); //EXC_BAD_ACCESS Here
            }
        }
    }
    void deflateReadOut(int x, int y, unsigned char* chunk) {

        int ret, flush;
        unsigned have;
        z_stream strm;
        unsigned char out[CHUNK];
        /* allocate deflate state */
        strm.zalloc = Z_NULL;
        strm.zfree = Z_NULL;
        strm.opaque = Z_NULL;
        ret = deflateInit(&strm, 1);
        if (ret != Z_OK);
        //return ret;
        ostringstream oss;
        oss << "map/" << x << "x" << y;
        string str = oss.str();
        FILE* dest = fopen(str.c_str(), "w");
        /* run deflate() on input until output buffer not full, finish
           compression if all of source has been read in */
        do {
            strm.avail_out = CHUNK;
            strm.next_in = chunk;
            strm.next_out = out;
            ret = deflate(&strm, flush); /* no bad return value */
            assert(ret != Z_STREAM_ERROR); /* state not clobbered */
            have = CHUNK - strm.avail_out;
            if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
                (void) deflateEnd(&strm);
                //return Z_ERRNO;
            }
        } while (strm.avail_out == 0);
        assert(strm.avail_in == 0); /* all input will be used */
        /* clean up and return */
        (void) deflateEnd(&strm);
    }

谢谢你给我的帮助

This:

chunk.reserve(4);
应:

chunk.resize(4);

否则，你只是在增加容量，而不是实际的向量大小。

还可以在初始化列表中初始化vector:

WSUMap() 
: chunk(4, vector<unsigned char>(CHUNK)) 
{
}

这相当于增加大小并初始化单个向量

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