用Valgrind检查了我的代码后，它显示了很多错误信息和信息，我不确定如何查找和删除代码中的错误？
我的源代码如下。
myheader.h
#include<stdlib.h>
#define MAX 15
typedef enum
{
METROPOLITAN_AREA,
TOURIST_AREA,
}area_type_t;
typedef struct
{
int population;
int area;
}metropolitan_t;
typedef struct
{
char *type_place;
char *near_airport;
}tourist_t;
typedef struct
{
char *name;
char *country;
area_type_t area_t;
union
{
metropolitan_t metro;
tourist_t tourist;
}u;
}*place_t;
extern void get_input(place_t);
getinput.c
#include<myheader.h>
void get_input(place_t place)
{
int check=1;
int num,i,ch;
printf("\nEnter the no of records : \n");
scanf("%d",&num);
place=(place_t)malloc(sizeof(place_t)*num);
if(NULL==place)
{
printf("\nMemory allocation failed\n");
exit(1);
}
for(i=0;i<num;i++)
{
printf("\nEnter the place name : ");
place->name=(char *)malloc(sizeof(char)*MAX);
if(NULL==place->name)
{
free(place);
printf("\nMemory allocation failed\n");
exit(1);
}
scanf("%s",place->name);
printf("\nEnter the coutry name : ");
place->country=(char *)malloc(sizeof(char)*MAX);
if(NULL==place->country)
{
free(place);
free(place->name);
printf("Memory allocation failed\n");
exit(1);
}
scanf("%s",place->country);
printf("\nPlease Enter '0' if the place is Metropolitan, '1' if the place Tourist place\n");
scanf("%d",&ch);
while(check)
{
switch(ch)
{
case 0:
check=0;
place->area_t=METROPOLITAN_AREA;
break;
case 1:
check=0;
place->area_t=TOURIST_AREA;
break;
default:
printf("\nPlease enter valid choice \n");
}
}
if(place->area_t==METROPOLITAN_AREA)
{
printf("\nEnter the population of the place : ");
scanf("%d",&(place->u.metro.population));
printf("\nEnter the area of place :");
scanf("%d",&(place->u.metro.area));
} else
{
printf("\nEnter the nearest airport name : ");
place->u.tourist.near_airport=(char *)malloc(sizeof(char)*MAX);
if(NULL==place->u.tourist.near_airport)
{
printf("Memory allocation failed\n");
exit(1);
}
scanf("%s",(place->u.tourist.near_airport));
printf("\nEnter the type of tourist spot : ");
place->u.tourist.type_place=(char *)malloc(sizeof(char)*MAX);
if(NULL==place->u.tourist.type_place)
{
printf("Memory allocation failed\n");
exit(1);
}
scanf("%s",(place->u.tourist.type_place));
}
check=1;
place++;
}
}
的main.c
#include"myheader.h"
int main()
{
place_t place;
get_input(place);
return 0;
}
命令行记录
bash-3.00$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes a.out
==13514== Memcheck, a memory error detector.
==13514== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al.
==13514== Using LibVEX rev 1575, a library for dynamic binary translation.
==13514== Copyright (C) 2004-2005, and GNU GPL'd, by OpenWorks LLP.
==13514== Using valgrind-3.1.1, a dynamic binary instrumentation framework.
==13514== Copyright (C) 2000-2005, and GNU GPL'd, by Julian Seward et al.
==13514== For more details, rerun with: -v
==13514==
Enter the no of records :
2
Enter the place name : Banglore
Enter the coutry name : India
Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
0
==13514== Invalid write of size 4
==13514== at 0x400789: get_input (getinput.c:43)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x400637: get_input (getinput.c:8)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 4
==13514== at 0x4007BB: get_input (getinput.c:53)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x400637: get_input (getinput.c:8)
==13514== by 0x4005E8: main (main.c:5)
Enter the population of the place : 303030
Enter the area of place :2500
==13514==
==13514== Invalid write of size 8
==13514== at 0x40068C: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
==13514==
==13514== Invalid read of size 8
==13514== at 0x400693: get_input (getinput.c:18)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
==13514==
==13514== Invalid read of size 8
==13514== at 0x4006BF: get_input (getinput.c:24)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
Enter the place name : London
==13514==
==13514== Invalid write of size 8
==13514== at 0x4006EE: get_input (getinput.c:26)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 8
==13514== at 0x4006F6: get_input (getinput.c:27)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 8
==13514== at 0x4006F6: get_input (getinput.c:27)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 8
==13514== at 0x40072F: get_input (getinput.c:34)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
Enter the coutry name : London
Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
1
==13514==
==13514== Invalid write of size 4
==13514== at 0x40079D: get_input (getinput.c:47)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D068 is 8 bytes before a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid write of size 8
==13514== at 0x40082F: get_input (getinput.c:62)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 8
==13514== at 0x400837: get_input (getinput.c:63)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== Invalid read of size 8
==13514== at 0x40085B: get_input (getinput.c:68)
==13514== by 0x4005E8: main (main.c:5)
==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
Enter the nearest airport name : London
Enter the type of tourist spot : Entertainment
==13514==
==13514== ERROR SUMMARY: 13 errors from 12 contexts (suppressed: 4 from 1)
==13514== malloc/free: in use at exit: 106 bytes in 7 blocks.
==13514== malloc/free: 7 allocs, 0 frees, 106 bytes allocated.
==13514== For counts of detected errors, rerun with: -v
==13514== searching for pointers to 7 not-freed blocks.
==13514== checked 75,768 bytes.
==13514==
==13514==
==13514== 15 bytes in 1 blocks are indirectly lost in loss record 1 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40088A: get_input (getinput.c:70)
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40088A: get_input (getinput.c:70)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514== 15 bytes in 1 blocks are definitely lost in loss record 2 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40082E: get_input (getinput.c:62)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514== 15 bytes in 1 blocks are definitely lost in loss record 3 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x4006ED: get_input (getinput.c:26)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514== 15 bytes in 1 blocks are definitely lost in loss record 4 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514== 15 bytes in 1 blocks are indirectly lost in loss record 5 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x4006ED: get_input (getinput.c:26)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514== 15 bytes in 1 blocks are indirectly lost in loss record 6 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x40068B: get_input (getinput.c:17)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514==
==13514==
==13514== 61 (16 direct, 45 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 7
==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149)
==13514== by 0x400637: get_input (getinput.c:8)
==13514== by 0x4005E8: main (main.c:5)
==13514==
==13514== LEAK SUMMARY:
==13514== definitely lost: 61 bytes in 4 blocks.
==13514== indirectly lost: 45 bytes in 3 blocks.
==13514== possibly lost: 0 bytes in 0 blocks.
==13514== still reachable: 0 bytes in 0 blocks.
==13514== suppressed: 0 bytes in 0 blocks.
如何解决此问题并使我的程序更节省内存？我使用的malloc()语句有什么问题吗？
答案 0 :(得分：5)
要做的第一件事是摆脱所有内存错误（缓冲区溢出）。第45行的get_input.c中发生了第一个错误，所以转到该行并弄清楚出了什么问题。
有一点肯定是错误的是这个
place=(place_t)malloc(sizeof(place_t)*num);
您正在分配一个place_t，但是您已经将place_t定义为：
typedef struct
{
}*place_t;
即。 place_t只是一个指针。这意味着，例如malloc（sizeof（place_t））只为指针分配空间，而不是为整个place_t分配空间。不要将结构名称隐藏为带有typedef的指针，但如果必须，请将malloc语句更改为
place=(place_t)malloc(sizeof *place)*num);
另一个问题是你释放（）结构，然后尝试访问其中的成员，这是无效的。
free(place);
free(place->name);
您必须按此顺序执行
free(place->name);
free(place);
你也在泄漏内存，例如这里： for（i = 0; iname =（char *）malloc（sizeof（char）* MAX）;
这个循环中的2.时间会发生什么？您分配给place->name，丢失指向您在循环的第一次迭代中分配的内存的指针。也许你打算在循环中使用place [num]，因为你试图在place =（place_t）malloc（sizeof（place_t）* num）中分配许多place_t;言。
答案 1 :(得分：4)
问题不在于malloc语句，而在于你完成它后释放内存的顺序。
e.g。
free(place);
free(place->name);
应该是
free(place->name);
free(place);
否则将不释放分配给name的内存。
同样，打电话
free(place);
不会释放分配的内存
place->name=(char *)malloc(sizeof(char)*MAX);
您必须手动释放分配给每个Malloc语句的内存。
在使用null再次使用它们之前，最好先检查指向内存位置的指针是否为malloc。
如果他们不是null，那么free他们，然后将其设置为null。这有助于确保您没有内存泄漏。