您的copy_range函数已损坏，因为它只复制指向大小和值的指针，而不复制内存。在调用
我正在编写一个c代码，该代码包含一个承载一些我称之为range的值的结构。
我的目的是动态地使用这个所谓的范围（在每次执行时保存不同数量的数据）。我现在暂时使用#define comp。每当我通过使用s1结构（和内存分配）调用update_range时，这个所谓的范围都会更新。
我发现奇怪的是，当我引入一个"show_range"函数来输出更新函数内外的实际值时，我意识到我丢失了前两个值。这是代码。对此有什么建议吗？提前感谢！
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <errno.h>
#include <string.h>
#include <complex.h>
#define comp 1024
// struct holding a complex-valued range
struct range {
int dimensions; /* number of dimensions */
int* size; /* array holding number of points per dimension */
complex double* values; /* array holding complex valued */
int components; /* number of components that will change on any execution*/
};
// parameters to use in function
struct s1 {
int tag;
struct range* range;
};
int update_range(struct s1* arg);
int show_range(struct range* argrange, char* message);
int copy_range(struct range* in, struct range* out);
int main(void) {
int ret = 0;
struct s1 s1;
s1.tag = 0;
s1.range = malloc(sizeof(struct range));
update_range(&s1);
show_range(s1.range, "s1.range inside main function");
return ret;
}
////////////////////////////////////////////
int update_range(struct s1* arg) {
int ret = 0;
int i;
struct range range;
range.dimensions = 1;
range.size = malloc(range.dimensions * sizeof(int));
range.components = comp;
range.size[0] = range.components; // unidimensional case
range.values = malloc(range.components * sizeof(complex double));
for (i = 0; i < range.components; i++) {
range.values[i] = (i + 1) + I * (i + 1);
}
show_range(&range, "range inside update_range function");
arg->range->size =
malloc(range.dimensions * sizeof(int)); // size was unknown before
arg->range->values =
malloc(comp * sizeof(complex double)); // amount of values was unknown
copy_range(&range, arg->range);
show_range(arg->range, "arg->range inside update_range function");
if (range.size)
free(range.size);
range.size = NULL;
if (range.values)
free(range.values);
range.values = NULL;
return ret;
}
////////////////////////////////////////////
// Show parameters (10 first values)
int show_range(struct range* argrange, char* message) {
int ret = 0;
vint i;
printf(" ******************************n");
printf(" range in %s n", message);
printf(" arg.dimensions=%d n", argrange->dimensions);
printf(" arg.size[0]=%d n", argrange->size[0]);
printf(" argrange.components=%d n", argrange->components);
printf(" first 10 {Re} values: n");
for (i = 0; i < 10; i++) {
printf(" argrange.values[%d]=%fn", i, creal(argrange->values[i]));
}
printf("n");
return ret;
}
////////////////////////////////////////////
// copy range
int copy_range(struct range* in, struct range* out) {
int ret = 0;
if (in == NULL) {
fprintf(stderr, "error: in points to NULL (%s:%d)n", __FILE__,
__LINE__);
ret = -1;
goto cleanup;
}
if (out == NULL) {
fprintf(stderr, "error: out points to NULL (%s:%d)n", __FILE__,
__LINE__);
ret = -1;
goto cleanup;
}
out->dimensions = in->dimensions;
out->size = in->size;
out->values = in->values;
out->components = in->components;
cleanup:
return ret;
}
free(range.size);和free(range.values);之后，您也从原始对象中删除了mamory，但没有将其指针设置回NULL。
调用update_range后，s1.range在大小和值上都有非NULL指针，但它们指向已删除的内存。
由于访问释放的内存，您正在经历未定义行为（UB）。copy_range()函数只执行两个指针字段的浅拷贝，因此当运行free(range->size)时，会使arg->range->size无效。
您应该通过分配和复制指针内容（如：）使copy_range()成为深度复制
out->size = malloc(in->dimensions * sizeof(int));
memcpy(out->size, in->size, in->dimensions * sizeof(int));
out->values = malloc(in->components * sizeof(complex double));
memcpy(out->values , in->values, in->components * sizeof(complex double));
There are not 10 items to print, so the lines:
printf(" first 10 {Re} values: n");
for (i = 0; i < 10; i++) {
printf(" argrange.values[%d]=%fn", i, creal(argrange->values[i]));
}
Will be printing from random memory.
a much better method would be:
printf(" first %d {Re} values: n", min(argrange.components,10));
for (i = 0; i < argrange.components; i++) {
printf(" argrange.values[%d]=%fn", i, creal(argrange->values[i]));
}
The above is just one of many problems with the code.
I would suggest executing the code using a debugger to get the full story.
as it is, the code has some massive memory leaks due mostly
to overlaying malloc'd memory pointers.
for instance as in the following:
arg->range->size =
malloc(range.dimensions * sizeof(int)); // size was unknown before
arg->range->values =
malloc(comp * sizeof(complex double)); // amount of values was unknown