运行c程序时出现以下错误：
*** Error in `./a.out': double free or corruption (!prev): 0x0000000000bb0470 ***
我相信这是因为在程序中调用了fclose（），它是一个用于c语言编译器的词法分析器，它使用文件指针。 这是代码：
#include<stdio.h>
#include<string.h>
typedef struct Terminal_table
{
int index;
char symbol[10],indicator;
}Terminal_table;
typedef struct Identifier_table
{
int index;
char name[10];
}Identifier_table;
typedef struct Literal_table
{
int SR,name,precision;
char base[10],scale[10];
}Literal_table;
typedef struct Uniform_symbol_table
{
int SR,index;
char name[10],symbol_class[10];
}Uniform_symbol_table;
int main()
{
FILE *fp_PGM,*fp_TT,*fp_LT,*fp_UST,*fp_IT,*fp_IT1,*fp_LT1;
Terminal_table TT;
Identifier_table IT,IT1;
Literal_table LT,LT1;
Uniform_symbol_table UST;
int i=0,flag,flag_IT,flag_LT,a;
char ch,buffer[10];
fp_PGM=fopen("PGM_LEX.txt","r");
fp_UST=fopen("UST.TXT","w");
fp_IT=fopen("IT.TXT","w");
fp_LT=fopen("LT.TXT","w");
UST.SR=1;
IT.index=1;
LT.SR=1;
for(i=0;i<10;i++)
buffer[i]='\0';
i=0;
while(!feof(fp_PGM))
{
ch=fgetc(fp_PGM);
if(isalpha(ch) || isdigit(ch))
buffer[i++]=ch;
else if(ch!='"')
{
flag=0;
fp_TT=fopen("TT.txt","r");
while(!feof(fp_TT))
{
fscanf(fp_TT,"%d %s %c\n",&TT.index,&TT.symbol,&TT.indicator);
if(strcmp(TT.symbol,buffer)==0)
{
flag=1;
strcpy(UST.name,buffer);
UST.index=TT.index;
if(TT.indicator=='Y')
strcpy(UST.symbol_class,"TRM");
else
strcpy(UST.symbol_class,"KEY");
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,UST.index);
break;
}
}
fclose(fp_TT);
if(flag==0)
{
if(isalpha(buffer[0]))
{
flag_IT=0;
fclose(fp_IT);
fp_IT1=fopen("IT.TXT","r");
while(!feof(fp_IT1))
{
fscanf(fp_IT1,"%d %s\n",&IT1.index,IT1.name);
if(strcmp(IT1.name,buffer)==0)
{
flag_IT=1;
break;
}
}
fclose(fp_IT1);
strcpy(UST.name,buffer);
UST.index=TT.index;
strcpy(UST.symbol_class,"IDN");
if(flag_IT==1)
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,IT1.index);
if(flag_IT==0)
{
fp_IT=fopen("IT.TXT","a");
strcpy(IT.name,buffer);
fprintf(fp_IT,"%d %s\n",IT.index++,IT.name);
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,IT.index-1);
fclose(fp_IT);
}
}
else if(isdigit(buffer[0]))
{
flag_LT=0;
fclose(fp_LT);
fp_LT=fopen("LT.TXT","r");
while(!feof(fp_LT))
{
fscanf(fp_LT,"%d %d %s %s %s\n",<1.SR,<1.name,<1.precision,<1.base,<1.scale);
a=atoi(buffer);
if(LT1.name==a)
{
flag_LT=1;
break;
}
}
fclose(fp_LT);
strcpy(UST.name,buffer);
UST.index=TT.index;
strcpy(UST.symbol_class,"LIT");
if(flag_LT==1)
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,LT1.SR);
if(flag_LT==0)
{
fclose(fp_LT);
fp_LT=fopen("LT.TXT","a");
LT.name=atoi(buffer);
LT.precision=2;
strcpy(LT.base,"DECIMAL");
strcpy(LT.scale,"FIXED");
strcpy(UST.name,buffer);
fprintf(fp_LT,"%d %d %d %s %s\n",LT.SR++,LT.name,LT.precision,LT.base,LT.scale);
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,LT.SR-1);
fclose(fp_LT);
}
}
}
for(i=0;i<10;i++)
buffer[i]='\0';
buffer[0]=ch;
fp_TT=fopen("TT.txt","r");
while(!feof(fp_TT))
{
fscanf(fp_TT,"%d %s %c\n",&TT.index,&TT.symbol,&TT.indicator);
if(strcmp(TT.symbol,buffer)==0)
{
strcpy(UST.name,buffer);
UST.index=TT.index;
strcpy(UST.symbol_class,"TRM");
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,UST.index);
break;
}
}
for(i=0;i<10;i++)
buffer[i]='\0';
fclose(fp_TT);
i=0;
}
else if(ch=='"')
{
buffer[0]=ch;
fp_TT=fopen("TT.txt","r");
while(!feof(fp_TT))
{
fscanf(fp_TT,"%d %s %c\n",&TT.index,&TT.symbol,&TT.indicator);
if(strcmp(TT.symbol,buffer)==0)
{
strcpy(UST.name,buffer);
UST.index=TT.index;
if(TT.indicator=='Y')
strcpy(UST.symbol_class,"TRM");
else
strcpy(UST.symbol_class,"KEY");
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,UST.index);
break;
}
}
fclose(fp_TT);
ch=fgetc(fp_PGM);
while(ch!='"')
{
ch=fgetc(fp_PGM);
}
strcpy(UST.name,buffer);
UST.index=TT.index;
if(TT.indicator=='Y')
strcpy(UST.symbol_class,"TRM");
else
strcpy(UST.symbol_class,"KEY");
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,UST.index);
ch=fgetc(fp_PGM);
}
}
fclose(fp_PGM);
fclose(fp_UST);
fclose(fp_IT);
fclose(fp_LT);
}
`./a.out'中的错误：双重免费或损坏（！prev）：0x0000000000bb0470
这个程序中有多个文件操作，它包括源程序（它是简单的c程序，没有预处理器），终端故事作为输入，这个文本文件需要在运行上面的代码之前创建
TT.txt =＆gt;
1 void N
2 main N
3 int N
4 float N
5 printf N
6 scanf N
7 , Y
8 ; Y
9 = Y
10 " Y
11 { Y
12 } Y
13 * Y
14 / Y
15 + Y
16 - Y
17 ( Y
18 ) Y
19 < Y
20 > Y
21 getch N
PGM_LEX.txt =＆gt;
void main()
{
int i=10,j;
printf("%d",i);
i=(j/10);
getch();
}
谢谢！
答案 0 :(得分：3)
除了其他问题，valgrind报告
==27338== Invalid read of size 4
==27338== at 0x4EA57D4: fclose@@GLIBC_2.2.5 (in /usr/lib64/libc-2.26.so)
==27338== by 0x400B32: main (gggg4.c:135)
==27338== Address 0x5211310 is 0 bytes inside a block of size 552 free'd
==27338== at 0x4C2DD18: free (vg_replace_malloc.c:530)
==27338== by 0x4EA587D: fclose@@GLIBC_2.2.5 (in /usr/lib64/libc-2.26.so)
==27338== by 0x400AFB: main (gggg4.c:127)
==27338== Block was alloc'd at
==27338== at 0x4C2CB6B: malloc (vg_replace_malloc.c:299)
==27338== by 0x4EA622C: __fopen_internal (in /usr/lib64/libc-2.26.so)
==27338== by 0x400E00: main (gggg4.c:116)
这两行是
127 fclose(fp_LT);
...
135 fclose(fp_LT);
答案 1 :(得分：2)
正如@ensc所提到的，在代码的第135行中，在if(flag_LT==0)案例中，您致电fclose(fp_LT)，但您已在第127行关闭它。
工具cppcheck也发现了这个错误。
您可以使用rewind()返回文件的开头，而不是重复打开和关闭同一文件。此外，您的计划未检查任何fopen()，fscanf()和fclose()来电的结果。这意味着如果您有损坏的数据，或者读取和写入文件有任何错误，您的程序将忽略这些错误，可能会产生不良后果。
答案 2 :(得分：1)
这部分看起来很可疑：
fclose(fp_LT); // fp_LT is closed
strcpy(UST.name,buffer);
UST.index=TT.index;
strcpy(UST.symbol_class,"LIT");
if(flag_LT==1)
fprintf(fp_UST,"%d %s %s %d \n",UST.SR++,UST.name,UST.symbol_class,LT1.SR);
if(flag_LT==0)
{
fclose(fp_LT); // fp_LT is closed again
如果flag_LT为零，则您似乎两次致电fclose。这是未定义的行为。