Question

正在静态链接到的库中调用函数（C99）。

在tests.c中：

int ok = solve_equation(&eq, &result);

在poly.c中：

int solve_equation(equation_integer_2 *eq, fraction *result) {...}

指针被传递给结构变量“eq”到函数中。当gdb进入函数时，其中一个struct的变量值 eq->poly->term3->coefficient 与以往不同。从调用代码到库，这个值似乎已经改变了。这是正确的吗？可能导致变化的原因是什么？

Gdb输出：

Breakpoint 1, test_solve_equation_1 () at tests.c:97
97      int ok = solve_equation(&eq, &result);
(gdb) p &eq->poly->term1->coefficient
$15 = (unsigned char *) 0x7fffffffd880 ""
(gdb) p &eq->poly->term2->coefficient
$16 = (unsigned char *) 0x7fffffffd890 "\002\001@"
(gdb) p &eq->poly->term3->coefficient
$17 = (unsigned char *) 0x7fffffffd8a0 ""
(gdb) s
solve_equation (eq=0x7fffffffd8f0, result=0x7fffffffd8d0) at poly.c:64
64          if (eq->poly->term1->coefficient == 0 && eq->poly->term3->coefficient == 0) {
(gdb) p &eq->poly->term1->coefficient
$18 = (unsigned char *) 0x7fffffffd880 ""
(gdb) p &eq->poly->term2->coefficient
$19 = (unsigned char *) 0x7fffffffd890 "\002\001@"
(gdb) p &eq->poly->term3->coefficient
$20 = (unsigned char *) 0x7fffffffd8a0 "\320\330\377\377\377\177"

术语（n）结构的构造如下：

void term_integer_factory(term_integer *t)                                                                                         |#include "number.h"
{                                                                                                                                  |
    t->coefficient = 0;                                                                                                            |typedef struct term_fraction
    t->degree = 1;                                                                                                                 |{
}

Answer 1

像Daniel和user5329483暗示的那样，问题在于struct初始化。函数内部有嵌套的struct初始化。我已将其更改为malloc所有相关结构（使用相应的free调用）并且它可以正常工作。

它被初始化为：

void polynomial_integer_2_factory(polynomial_integer_2 *p) 
{
    term_integer t1;
    term_integer_factory(&t1);
    t1.degree = 2;
    p->term1 = &t1;
    term_integer t2;
    term_integer_factory(&t2);
    t2.degree = 1;
    p->term2 = &t2;
    term_integer t3;
    term_integer_factory(&t3);
    t3.degree = 0;
    p->term3 = &t3;
}

现在它被初始化为：

polynomial_integer_2* create_polynomial_integer_2() 
    polynomial_integer_2 *p = malloc(sizeof *p);
    if (!p) {}
    term_integer *t1 = create_term_integer();
    t1->degree = 2;
    p->term1 = t1;
    term_integer *t2 = create_term_integer();
    t2->degree = 1;
    p->term2 = t2;
    term_integer *t3 = create_term_integer();
    t3->degree = 0;
    p->term3 = t3;
    return p;
}

在步入库时更改结构值

1 个答案: