Question

我一直在努力解决这个问题，我无法弄清楚出了什么问题。这是代码：

//the code for the function that is being called
//charset is a const char[] consisting of 91 characters
//charset_size is 91
void set_sequence(char keyword[], int keyword_size){

    sequence = malloc(keyword_size);

    int i = 0, j = 0;

    for(i = 0; i < keyword_size; i++){

        for(j = 0; j < charset_size; j++){

            if(keyword[i] == charset[j]){

                sequence[i] = j;

            }

        }

    }

    sequence_size = keyword_size;

}

//the function call in main
set_sequence("foo bar\n", 8);

//there's supposed to be stuff done here with sequence that I haven't implemented yet
free(sequence); //sequence is a global variable that I use the function to set

FILE* dest = fopen("cipher", "w");

我包含文件位的原因是因为当它存在时，我得到断言失败，但是当它被注释掉时，代码运行得非常好（在那行之后我什么都没有，因为我试图查明问题）。 / p>

我通过valgrind的memcheck valgrind --tool=memcheck ../bin/cipher运行代码来查看问题所在，但我无法理解它。这是输出：

==10608== Memcheck, a memory error detector
==10608== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==10608== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==10608== Command: ../bin/cipher -e testfile
Program running in encrypt mode
Open source file: success
Allocate memory for raw_input: success
Read source file: success
Allocate memory for input: success
input set-> freeing raw_input
==10608== Invalid write of size 4
==10608==    at 0x80486DC: set_sequence (in /home/hugo/Programming/C++/Cipher
==10608==    by 0x8048A86: main (in /home/hugo/Programming/C++/Cipher/bin/cipher)
==10608==  Address 0x41f6688 is 0 bytes inside a block of size 8 alloc'd
==10608==    at 0x402BB7A: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==10608==    by 0x804868C: set_sequence (in /home/hugo/Programming/C++/Cipher/bin/cipher
==10608==    by 0x8048A86: main (in /home/hugo/Programming/C++/Cipher/bin/cipher)
==10608== 
==10608== HEAP SUMMARY:
==10608==     in use at exit: 704 bytes in 2 blocks
==10608==   total heap usage: 6 allocs, 4 frees, 1,793 bytes allocated
==10608== 
==10608== LEAK SUMMARY:
==10608==    definitely lost: 0 bytes in 0 blocks
==10608==    indirectly lost: 0 bytes in 0 blocks
==10608==      possibly lost: 0 bytes in 0 blocks
==10608==    still reachable: 704 bytes in 2 blocks
==10608==         suppressed: 0 bytes in 0 blocks
==10608== Rerun with --leak-check=full to see details of leaked memory
==10608== 
==10608== For counts of detected and suppressed errors, rerun with: -v
==10608== ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 0 from 0)

Answer 1

你没有给出序列声明。它是char数组还是int数组？如果它是一个int数组，那么你的malloc是错误的，它需要分配keyword_size * sizeof(int)个字节

打开文件会导致sYSMALLOc断言失败

1 个答案: