Question

我正在运行一个代码来计算和打印卡方和文件的卡方密度文件的值;但是我的问题是我在屏幕输出结束时得到了一个分段错误错误，即使点数相对较少，例如100,500等。我已经编写了一个代码，它使用了更多的数字并运行没有问题。如果您指出错误并指导我完成补救过程，我将不胜感激。当我尝试使用malloc时，我得到一个不同的错误如下：

*** glibc detected *** ./Q4: munmap_chunk(): invalid pointer: 0x0a026978 ***
======= Backtrace: =========
/lib/i386-linux-gnu/libc.so.6(+0x75ee2)[0xb7653ee2]
/lib/i386-linux-gnu/libc.so.6(+0x765c5)[0xb76545c5]
/lib/i386-linux-gnu/libc.so.6(fclose+0x154)[0xb7643424]
./Q4[0x80488b9]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb75f74d3]
./Q4[0x8048501]
======= Memory map: ========
08048000-08049000 r-xp 00000000 08:08 393219     /home/ongun/Desktop/Dropbox/Computational Physics/PHYS443-MT1/Q4
08049000-0804a000 r--p 00000000 08:08 393219     /home/ongun/Desktop/Dropbox/Computational Physics/PHYS443-MT1/Q4
0804a000-0804b000 rw-p 00001000 08:08 393219     /home/ongun/Desktop/Dropbox/Computational Physics/PHYS443-MT1/Q4
0a026000-0a047000 rw-p 00000000 00:00 0          [heap]
b75a2000-b75be000 r-xp 00000000 08:06 131773     /lib/i386-linux-gnu/libgcc_s.so.1
b75be000-b75bf000 r--p 0001b000 08:06 131773     /lib/i386-linux-gnu/libgcc_s.so.1
b75bf000-b75c0000 rw-p 0001c000 08:06 131773     /lib/i386-linux-gnu/libgcc_s.so.1
b75dc000-b75de000 rw-p 00000000 00:00 0 
b75de000-b7782000 r-xp 00000000 08:06 137731     /lib/i386-linux-gnu/libc-2.15.so
b7782000-b7784000 r--p 001a4000 08:06 137731     /lib/i386-linux-gnu/libc-2.15.so
b7784000-b7785000 rw-p 001a6000 08:06 137731     /lib/i386-linux-gnu/libc-2.15.so
b7785000-b7788000 rw-p 00000000 00:00 0 
b7788000-b77b2000 r-xp 00000000 08:06 137726     /lib/i386-linux-gnu/libm-2.15.so
b77b2000-b77b3000 r--p 00029000 08:06 137726     /lib/i386-linux-gnu/libm-2.15.so
b77b3000-b77b4000 rw-p 0002a000 08:06 137726     /lib/i386-linux-gnu/libm-2.15.so
b77ce000-b77d2000 rw-p 00000000 00:00 0 
b77d2000-b77d3000 r-xp 00000000 00:00 0          [vdso]
b77d3000-b77f3000 r-xp 00000000 08:06 137721     /lib/i386-linux-gnu/ld-2.15.so
b77f3000-b77f4000 r--p 0001f000 08:06 137721     /lib/i386-linux-gnu/ld-2.15.so
b77f4000-b77f5000 rw-p 00020000 08:06 137721     /lib/i386-linux-gnu/ld-2.15.so
bfc86000-bfca7000 rw-p 00000000 00:00 0          [stack]
Aborted (core dumped)

我的代码如下：

#include <stdio.h>
#include <math.h>
#include <limits.h>
#include <stdlib.h>
#define N 100
// We have three function definitions here
// The factorial function decleration and definition are as follows:
long double factorial (long double);
// Now we define it,
long double
factorial(long double n)
{
    //Here s is the free parameter which is increased by one in each step and
    //pro is the initial product and by setting pro to be 0 we also cover the
    //case of zero factorial.
    int s = 1;
    long double pro = 1;
    //Here pro stands for product.
    if (n < 0)
        printf("Factorial is not defined for a negative number \n");
    else {
    while (n >= s) { 
    pro *= s;
    s++;
    }
    return pro;
    }
}
// The Gamma function declaration and definition are as follows:
long double GAMMA_2(int);
long double 
GAMMA_2(int v)
{
    int i = 1;
    long double factor, multiplier =  sqrtl(M_PI);
    if((v % 2) == 0)
    {
        return factorial((long double )((v / 2) - 1));
    }
    else
    {
        factor = (v / 2.0) - i;
        while(v / 2.0 - (i) > 0)
        {

            factor = (v / 2.0 - i); 
            multiplier *= factor;
            i++;
        }
        return multiplier;
    }
}
// The ChisquarePDF declaration and definition are as follows:
long double ChisquarePDF(long double, int);
long double
ChisquarePDF(long double x, int v)
{
    return powl(x, v/2 - 1) / ( powl(2, v/2) * GAMMA_2(v) * expl(x / 2));
}
int main()
{
    //This is the trial line
    //printf("%Lf \n", GAMMA_2(9));
    int i, v = 10;
    //long double * x = malloc(N* sizeof(long double));
    //long double * y = malloc(N* sizeof(long double));
    long double x[N], y[N];
    // The Chisquare function is defined for positive values of x
    FILE * fp;
    fp = fopen("Q4.dat", "w+");
    for(i = 0; i <= N; i++)
    {
        x[i] = i / 10.0;
        y[i] = ChisquarePDF(x[i], v);
        //printf("%Le             %Le \n", x[i], y[i]);
        fprintf(fp, "%Le             %Le \n", x[i], y[i]);
    }
    //for(i = 0; i <= N; i++)
    //{
        //y[i] = ChisquarePDF(x[i], v);
        //printf("%Le             %Le \n", x[i], y[i]);
        //fprintf(fp, "%Le             %Le \n", x[i], y[i]);
    //}

    fclose(fp);
    //free((void *)x);
    //free((void *)y);
    return 0;
}

Answer 1

在main for循环中，i等于N，因此阅读＆amp;写入x[N]和y[N]，这超出了分配的数组。（对于使用大小N声明的数组：int array[N];，您可以访问array[0]到（包括）array[N-1]的元素。所以array[N]超出了for(i = 0; i < N; i++)那）。将循环条件更改为：

factorial

另外，我收到warning: control reaches end of non-void function的警告，告知它到达终点而没有返回有效值（if(n < 0)）。即使没有为负数定义阶乘（在if(n < 0){ printf("Factorial is not defined for a negative number \n"); return 0; }else{ ...内），您也必须返回一个值：

{{1}}

低迭代次数C中的分段错误

1 个答案: