c - 为什么运行程序会出错？

Question

我有一个错误，我找不到解决它的方法。我得到这个错误

Exception thrown at 0x504A3E6C (ucrtbased.dll) in ConsoleApplication3.exe: 0xC0000005: Access violation reading location 0x0047617A. On line 11.

#include "Entities.h"
#include<assert.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

Expense* createExp(int nr_ap, float price, char* type) {
    Expense *e = malloc(sizeof(Expense));
    e->nr_ap = nr_ap;
    e->price = price;
    e->type = malloc(sizeof(char)*strlen(type) + 1);  #Here is the problem.
    strcpy(e->type, type);
    return e;
}

void destroy(Expense *e) {
    free(e->type);
    free(e);

}

int getAp(Expense *e) {
    return e->nr_ap;
}

float getPrice(Expense *e) {
    return e->price;
}

char* getType(Expense *e) {
    return e->type;
}

/*
Create a copy
*/

Expense *copyExp(Expense *e) {
    return createExp(e->nr_ap, e->price, e->type);
}

void testCreateExp() {
    Expense *e = createExp(10, 120, 'Gaz');
    assert(getAp(e) == 10);
    assert(getPrice(e) == 12);
    assert(getType(e) == "Gaz");
    destroy(e);

}

int main() {
    testCreateExp();
}

Answer 1

Expense *e = createExp(10, 120, 'Gaz'); 没有意义。单引号用于单个字符，而不是 C 字符串。

例如char initial = 'G'; char* name = "Gaz";

尝试 Expense *e = createExp(10, 120, "Gaz");。大多数编译器应该警告您在这种情况下使用单引号是不正确的。

还怀疑您的断言不是“预期的” assert(getType(e) == "Gaz"); - 不应该是 strcmp() ？