当我致电print_token()时，我的应用程序崩溃了。我花了一整天试图解决这个没有成功，我放弃了。帮助
//#include "memory.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct TOKEN
{
int type;
char *str;
};
#define TOKEN_SIZE sizeof(struct TOKEN)
struct TOKEN *ini;
struct TOKEN *cur;
struct TOKEN *end;
int size = TOKEN_SIZE * 1;
void init_token_buffer(void);
void save_token(int type, const char *str);
void print_tokens(void);
void init_token_buffer(void)
{
ini = (struct TOKEN*) malloc(size); // 8 bytes...
cur = ini;
end = ini + size;
}
void save_token(int type, const char *str)
{
printf("cur == end : %d\n", cur == end);
if (cur == end)
{
int lastSize = (end - ini);
int newSize = size + lastSize;
ini = (struct TOKEN*) realloc(ini, newSize); // 16,24,32...
end = ini + newSize;
cur = ini + lastSize;
printf("l:%d, n:%d\n", lastSize, newSize);
}
int strSize = strlen(str) * sizeof(char) + sizeof(char);
char *newStr = (char*) malloc(strSize);
cur->str = (char*) memcpy(newStr, str, strSize);
cur->type = type;
printf("string:%s, type:%X\n", cur->str, cur->type);
// here it prints right!
cur += TOKEN_SIZE;
}
void print_tokens()
{
int i;
int total = (cur - ini);
printf("\ntotal tokens:%d\n", total / TOKEN_SIZE);
printf("total bytes:%d\n", total);
for (i = 0; i < total; i += TOKEN_SIZE)
{
struct TOKEN *t = &ini[i];
printf("string:%s, type:%X\n", t->str, t->type);
// here it crashes at the 2º loop! (ini[8])
}
}
您可以测试为：
main() {
init_token_buffer();
save_token(0, "aaa");
save_token(0, "bbb");
save_token(0, "ccc");
save_token(0, "ddd");
print_tokens();
}
答案 0 :(得分：4)
以下两点是你的错误：
由于ini的类型为TOKEN *，因此其访问索引是sizeof TOKEN的倍数。您必须了解pointer arithmetics。
我还建议您至少查看编译器警告：
$ gcc -Wall -pedantic -o test ./test.c
./test.c: In function ‘init_token_buffer’:
./test.c:26:38: warning: C++ style comments are not allowed in ISO C90 [enabled by default]
./test.c:26:38: warning: (this will be reported only once per input file) [enabled by default]
./test.c: In function ‘save_token’:
./test.c:46:2: warning: ISO C90 forbids mixed declarations and code [-pedantic]
./test.c: In function ‘print_tokens’:
./test.c:62:40: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat]
./test.c: In function ‘main’:
./test.c:81:1: warning: control reaches end of non-void function [-Wreturn-type]
...并且可能使用valgrind或类似工具检查程序是否存在运行时错误：
$ valgrind ./test
==9732== Memcheck, a memory error detector
==9732== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==9732== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for copyright info
==9732== Command: ./test
==9732==
cur == end : 0
string:aaa, type:0
cur == end : 1
l:16, n:32
==9732== Invalid write of size 8
==9732== at 0x400769: save_token (in /tmp/test)
==9732== by 0x40089B: main (in /tmp/test)
==9732== Address 0x51ce1e8 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid write of size 4
==9732== at 0x400777: save_token (in /tmp/test)
==9732== by 0x40089B: main (in /tmp/test)
==9732== Address 0x51ce1e0 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 4
==9732== at 0x400780: save_token (in /tmp/test)
==9732== by 0x40089B: main (in /tmp/test)
==9732== Address 0x51ce1e0 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 8
==9732== at 0x400789: save_token (in /tmp/test)
==9732== by 0x40089B: main (in /tmp/test)
==9732== Address 0x51ce1e8 is not stack'd, malloc'd or (recently) free'd
==9732==
string:bbb, type:0
cur == end : 1
l:32, n:48
==9732== Invalid write of size 8
==9732== at 0x400769: save_token (in /tmp/test)
==9732== by 0x4008AA: main (in /tmp/test)
==9732== Address 0x51ce398 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid write of size 4
==9732== at 0x400777: save_token (in /tmp/test)
==9732== by 0x4008AA: main (in /tmp/test)
==9732== Address 0x51ce390 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 4
==9732== at 0x400780: save_token (in /tmp/test)
==9732== by 0x4008AA: main (in /tmp/test)
==9732== Address 0x51ce390 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 8
==9732== at 0x400789: save_token (in /tmp/test)
==9732== by 0x4008AA: main (in /tmp/test)
==9732== Address 0x51ce398 is not stack'd, malloc'd or (recently) free'd
==9732==
string:ccc, type:0
cur == end : 1
l:48, n:64
==9732== Invalid write of size 8
==9732== at 0x400769: save_token (in /tmp/test)
==9732== by 0x4008B9: main (in /tmp/test)
==9732== Address 0x51ce558 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid write of size 4
==9732== at 0x400777: save_token (in /tmp/test)
==9732== by 0x4008B9: main (in /tmp/test)
==9732== Address 0x51ce550 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 4
==9732== at 0x400780: save_token (in /tmp/test)
==9732== by 0x4008B9: main (in /tmp/test)
==9732== Address 0x51ce550 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 8
==9732== at 0x400789: save_token (in /tmp/test)
==9732== by 0x4008B9: main (in /tmp/test)
==9732== Address 0x51ce558 is not stack'd, malloc'd or (recently) free'd
==9732==
string:ddd, type:0
total tokens:4
total bytes:64
string:aaa, type:0
==9732== Invalid read of size 4
==9732== at 0x400843: print_tokens (in /tmp/test)
==9732== by 0x4008BE: main (in /tmp/test)
==9732== Address 0x51ce350 is not stack'd, malloc'd or (recently) free'd
==9732==
==9732== Invalid read of size 8
==9732== at 0x400849: print_tokens (in /tmp/test)
==9732== by 0x4008BE: main (in /tmp/test)
==9732== Address 0x51ce358 is not stack'd, malloc'd or (recently) free'd
==9732==
string:(null), type:0
string:(null), type:0
string:ddd, type:0
==9732==
==9732== HEAP SUMMARY:
==9732== in use at exit: 80 bytes in 5 blocks
==9732== total heap usage: 8 allocs, 3 frees, 176 bytes allocated
==9732==
==9732== LEAK SUMMARY:
==9732== definitely lost: 12 bytes in 3 blocks
==9732== indirectly lost: 0 bytes in 0 blocks
==9732== possibly lost: 0 bytes in 0 blocks
==9732== still reachable: 68 bytes in 2 blocks
==9732== suppressed: 0 bytes in 0 blocks
==9732== Rerun with --leak-check=full to see details of leaked memory
==9732==
==9732== For counts of detected and suppressed errors, rerun with: -v
==9732== ERROR SUMMARY: 18 errors from 14 contexts (suppressed: 4 from 4)
以下是您的计划的外观：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct TOKEN
{
int type;
char *str;
};
struct TOKEN *ini = NULL;
struct TOKEN *cur = NULL;
struct TOKEN *end = NULL;
static void save_token(int type, const char *str)
{
struct TOKEN *p;
size_t n;
char *s;
if (cur == end) {
n = (size_t)(end - ini) + 1;
p = realloc(ini, n * sizeof(struct TOKEN));
if (!p) {
/* Out of memory??? */
abort();
}
cur = p + (cur - ini);
ini = p;
end = p + n;
}
if (!(s = strdup(str))) {
/* SOS! */
abort();
}
cur->str = s;
cur->type = type;
++cur;
}
static void print_tokens()
{
struct TOKEN *i = ini;
struct TOKEN *e = end;
printf("Total tokens: %ld\n", (e - i));
printf("Total bytes: %ld\n", (e - i) * sizeof(struct TOKEN));
while (i < e) {
printf("string:%s, type:%X\n", i->str, i->type);
++i;
}
}
static void clear_tokens()
{
struct TOKEN *i = ini;
struct TOKEN *e = end;
if (!ini)
return;
while (i < e) {
if (i->str)
free(i->str);
++i;
}
free(ini);
ini = cur = end = NULL;
}
int main() {
save_token(0, "aaa");
save_token(1, "bbb");
save_token(2, "ccc");
save_token(3, "ddd");
print_tokens();
clear_tokens(); /* Do not forget to clean up resources! */
return 0;
}
我感谢你努力学习C.你的代码虽然看起来部分是C99，部分是预先ANSI C，部分是C ++ :-D我建议你获得一些好的C书，并首先摆脱IDE ，它介于你和编译器之间。当然，您仍然可以将它用作编辑器，但尝试使用命令行工具进行编译并了解正在发生的事情......
祝你好运！