求助：c++出错~~ 0xC0000005: 写入位置 0xCDCDCDCD 时发生访问冲突

[susan-wang]

想要对矩阵进行LU分解，出现报错，调试不知如何修改，请大神帮忙啊！！

// LU sequential.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int size;
double **l;
double **u;
double **mat;
clock_t t1,t2;
FILE *fp;


void decompose(double **m) {
	t1 = clock();
	int i = 0, j = 0, k = 0;
	for (j = 0; j < size - 1; j++) {
		for (i = j + 1; i < size; i++) {
			double factor = m[i][j] / m[j][j];
			for (k = 0; k < size; k++) {
				u[i][k] = m[i][k] - (m[j][k] * factor);
			}
			l[i][j] = factor;
		}

		for (i = 0; i < size; i++) {
			for (k = 0; k < size; k++) {
				m[i][k] = u[i][k];
			}
		}

		t2 = clock();
	}
}

int generateMatrix(int size){
	srand((unsigned) time(NULL));
	mat =new double*[size * (sizeof *mat)];
	u = new double*[size * (sizeof *u)]; 
	l = new double*[size * (sizeof *l)]; 
	
	int i = 0;
	for (i = 0; i < size; i++) {
		u[i] = new double[(sizeof *u[i]) * size];
		l[i] = new double[(sizeof *l[i]) * size];
		mat[i] = new double[(sizeof *mat[i]) * size];
		

		int j = i;
		for (j = i; j< size; j++) {
			mat[i][j] = i + 1;
			mat[j][i] = i + 1;
			u[i][j] = mat[i][j];
			u[j][i] = mat[j][i];
		}
	}
	decompose(mat);
	
	return 1;
}


int main(int argc, char * argv[])
{

	size =100;
	fopen_s(&fp,"output.txt", "a+");


	int successFlag = 0;
	if (generateMatrix(size) == 1)
	{
		successFlag = 1;
	}
	delete[]mat;
	delete[]u;
	delete[]l;
	fprintf(fp, "%d ", size);
	fprintf(fp, "%f\n", (double)(t2 - t1) / CLOCKS_PER_SEC);
	fclose(fp);
	return 0;
}

错误提示：

[爱的新风]

你这应该是访问了非法内存

[paschen]

点中断，通过调用堆栈定位出错的位置，然后分析导致的原因

[FightForProgrammer]

看调试信息。一层一层跟踪，找到出错的地方