C 在程序结束时检测到堆栈崩溃
当我试图通过C 在程序结束时检测到堆栈崩溃,c,arrays,struct,dynamic-memory-allocation,C,Arrays,Struct,Dynamic Memory Allocation,当我试图通过返回0退出程序时,我正在以较小的规模测试一个程序,以区分问题位于主函数的末尾 Main.c #include <stdio.h> #include <stdlib.h> #include "Header.h" int main (void) { int i; int Fin = 0; Student sStu; Array aAry; Student *Stu = &
返回0退出程序时,我正在以较小的规模测试一个程序,以区分问题代码>位于主函数的末尾
Main.c
#include <stdio.h>
#include <stdlib.h>
#include "Header.h"
int main (void)
{
int i;
int Fin = 0;
Student sStu;
Array aAry;
Student *Stu = &sStu;
Array *Ary = &aAry;
InitArray(Ary, 1);
while(Fin != 2)
{
printf("Please choose a selection.\n");
printf("1. Add Student\n");
printf("2. Print Students\n");
printf("3. Exit\n");
scanf("%d", &i);
switch(i)
{
case 1:
{
AddStudent(Stu, Ary);
break;
}
case 2:
{
for(i = 0; i < Ary->Size; i++)
{
printf("%s %d\n", Stu[i].Name, Stu[i].IDn);
}
break;
}
case 3:
{
return 0;
}
}
}
}
c级
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "Header.h"
void InitArray(Array *Ary, int InitSize)
{
Ary->Student = malloc(InitSize * sizeof(Student));
Ary->Used = 0;
Ary->Size = InitSize;
memset(&Ary->Student[0], 0 , sizeof(Student) * InitSize);
}
void AddArray(Array *Ary)
{
Student Stud;
if(Ary->Used == Ary->Size)
{
Ary->Size *= 2;
Ary->Student = realloc(Ary->Student, Ary->Size * sizeof(Student));
}
strcpy(Ary->Student[Ary->Used].Name, Stud.Name);
Ary->Student[Ary->Used].IDn = Stud.IDn;
Ary->Used++;
}
Student AddStudent(Student *Stu, Array *Ary)
{
int i;
printf("\nStudent ID numbers cannot be the same!\n");
printf("Please enter the student's name: ");
scanf("%s", Stu[Ary->Used].Name);
printf("Please enter the student's ID Number: ");
scanf("%d", &Stu[Ary->Used].IDn);
AddArray(Ary);
printf("\n");
return;
}
valgrind在我尝试退出程序时由于致命错误而终止
它只发生在最后,我可以正确打印结构数组的内容。我已经研究了realloc()因为我相当肯定错误就在这里面,但是我不确定我到底做错了什么。我试图改变InitArray()中分配内存的方式代码>和我使用realloc()的方式代码>但无效
我做错了什么?您当前的问题是试图使用“无效指针”。(实际上,这是一个完全有效的指针,它只是指向一个错误的位置)
sStu
是一个Student
,而Stu
是指向它的指针。但是,当您添加第二个学生时,您将写入Stu[1]
——这是sStu
之后的空格。很可能这个空间中还有其他内容,所以当您向Stu[1]
写入时,您会覆盖其他内容。(这个空间里到底会有什么是不可预测的。)
看起来你想在你所有的Stu
地方都使用ari->Student
(如果这样做,您可能会发现更多的问题-例如,在写入下一个元素后检查是否需要扩展数组)Valgrind说segfault发生在AddArray
中的strcpy
。使用-g
编译以显示行号。好的,谢谢。我要去试试,我想这是因为我以前的老师教过我这样做。在我看来,我想读起来更清楚。scanf(“%s”,Stu[Ary->Used].Name)代码>。看起来您正在将单个(堆栈分配)Student
传递到Addstudent
中,但随后将其用作Student
s的数组。main()
中的Fin
在使用其值时未初始化。未定义的行为。谢谢,这解决了我问题中的问题,正如你所预测的,还造成了一些问题。谢谢你@Arrowkill不是“造成的”,但可能是“暴露的”。从这个意义上说,你是对的,尽管我的措辞选择不当,但这正是我的意思。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "Header.h"
void InitArray(Array *Ary, int InitSize)
{
Ary->Student = malloc(InitSize * sizeof(Student));
Ary->Used = 0;
Ary->Size = InitSize;
memset(&Ary->Student[0], 0 , sizeof(Student) * InitSize);
}
void AddArray(Array *Ary)
{
Student Stud;
if(Ary->Used == Ary->Size)
{
Ary->Size *= 2;
Ary->Student = realloc(Ary->Student, Ary->Size * sizeof(Student));
}
strcpy(Ary->Student[Ary->Used].Name, Stud.Name);
Ary->Student[Ary->Used].IDn = Stud.IDn;
Ary->Used++;
}
Student AddStudent(Student *Stu, Array *Ary)
{
int i;
printf("\nStudent ID numbers cannot be the same!\n");
printf("Please enter the student's name: ");
scanf("%s", Stu[Ary->Used].Name);
printf("Please enter the student's ID Number: ");
scanf("%d", &Stu[Ary->Used].IDn);
AddArray(Ary);
printf("\n");
return;
}
==9966== Invalid write of size 1
==9966== at 0x402C6C3: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==9966== by 0x8048687: AddArray (in /home/ctj0033/CSCE_1040/Homework/2_Homework/2_Test/a.out)
==9966== by 0x804874B: AddStudent (in /home/ctj0033/CSCE_1040/Homework/2_Homework/2_Test/a.out)
==9966== by 0x804881C: main (in /home/ctj0033/CSCE_1040/Homework/2_Homework/2_Test/a.out)
==9966== Address 0x41f804c is 0 bytes after a block of size 36 alloc'd