存储在C结构中的值“神奇地”自行更改。

Question

我有以下类型的结构(带嵌套)：

typedef struct {
   float precursor_mz;
   float precursor_int;
   int scan;
   float time;
   spectrum* spectra; /* Nested struct */
   int array_length;
   int mz_length;
   int int_length;
   char* mz_binary;
   char* int_binary;
   int hits;
} compound;
typedef struct {
   float mz_value;
   float int_value;
   int peaks;
} spectrum;

我转换这个结构以允许我使用qsort，然后我将它作为我自己的“类型”存储回来。在代码后面的几行代码中，我希望对结构进行循环，但是在没有访问它们(中间)的情况下，值发生了某种变化。下面的代码片段：

    // The transformating & qsort chunk
    for (i = 0; i < compounds->hits; i++) {
       spectrum test[(compounds+i)->spectra->peaks];
       for (j = 0; j < (compounds+i)->spectra->peaks; j++) {
           test[j] = *((compounds+i)->spectra+j);
       }
       qsort(test,(compounds+i)->spectra->peaks,sizeof(spectrum),compare_mz);
       for (j = 0; j < (compounds+i)->spectra->peaks; j++) {
           ((compounds+i)->spectra+j)->mz_value = test[j].mz_value;
           ((compounds+i)->spectra+j)->int_value = test[j].int_value;
           if ( j < 10) {
               printf("%i %i\t", i, j);
               printf("%f %f\n",((compounds+i)->spectra+j)->mz_value, ((compounds+i)->spectra+j)->int_value); // Here values are still correct 
           } 
       }
   }


/* Summing values that are in 'mass-tolerance' of each other */
   float int_total;
   float mz_int_total;
   for (i = 0; i < compounds->hits; i++) {
       counter = 0;
       printf("---\n");
       for (j = 0; j < (compounds+i)->spectra->peaks; j++) {
           lower_mass = ((compounds+i)->spectra+j)->mz_value - 0.05; //args->mass_tolerance;
           upper_mass = ((compounds+i)->spectra+j)->mz_value + 0.05; //args->mass_tolerance;
           if (j < 10) { 
               printf("%i %i\t", i , j);
               printf("%f %f\n",((compounds+i)->spectra+j)->mz_value, ((compounds+i)->spectra+j)->int_value);  // Here values are borked
           } 
           // Rest of the code chopped off as it should be irrelevant

但是，此代码产生以下输出：

tarskin@5-PARA-11-0120:/data/programming/C/Compound_Spectra$ ./Run -f ../PeptMoiety/32757_p_01.mzML -c 1
0 0 168.858765 32489.994141
0 1 168.960327 72930.046875
0 2 169.039993 4924.188477
0 3 169.913681 85340.171875
0 4 169.932312 2406.798096
0 5 171.000320 345949.593750
0 6 171.007950 1034718.312500
0 7 171.034088 882886.562500
0 8 171.034378 58554.589844
0 9 171.056320 871035.500000
---
0 0 168.858765 32489.994141
0 1 168.960327 72930.046875
0 2 169.039993 4924.188477
0 3 169.913681 85340.171875
0 4 0.000000 0.000000
0 5 169.932312 2406.798096
0 6 171.007950 1034718.312500
0 7 0.000000 0.000000
0 8 0.000000 0.000000
0 9 0.000000 0.000000

有人知道会发生什么事吗？

--编辑1 --

Alk请求compare_mz的代码，如下所示：

int
compare_mz (const void *a, const void *b)
{
  const spectrum *fa = (const spectrum *) a;
  const spectrum *fb = (const spectrum *) b;

  return (fa->mz_value > fb->mz_value)
             -(fa->mz_value < fb->mz_value);
}

我展示的测试用例是单个化合物(所以i= 1)。

Answer 1

我强烈地认为，spectrum* spectra; /* Nested struct */引用的内存没有被正确分配，或者(部分)被释放。

尝试使用valgrind运行您的应用程序。

此外(如果您正在使用gcc)：如果使用gcc的-Wall和/或-pedantic选项，您会收到编译器警告吗？

尝试下面的mod/并查看应用程序/的行为是否不同(这样不会在to for (j=0;..;..)循环之间接触堆栈)：

float int_total;
float mz_int_total;
spectrum test[(compounds+i)->spectra->peaks];

for (i = 0; i < compounds->hits; i++) {
  ...

/* Summing values that are in 'mass-tolerance' of each other */    
for (i = 0; i < compounds->hits; i++) {
  ...