3

过去两天我一直在研究这个问题，但似乎无法找出问题所在。

我正在从文件中读取并将其作为字符串保存到 char 数组中，但是当我尝试strlen()在字符串上使用时，它会因分段错误而崩溃。

这就是我正在做的事情。

char read_string[25];
fscanf(file, "%s", &read_string);
int length = strlen(read_string);

另一个问题是，当我将 的内容复制read_string到另一个 char 数组中时，它会在末尾添加随机字符。

这是我正在做的

char input[25];
for(i=0; i<25; i++)
{
    if (read_string[i] == '.')
        break;
    else
        input[i] = read_string[i];
}

我需要在句点将字符串读入输入数组之前复制所有内容。

PS我正在使用fscanf()，因为该文件结构良好。

如果需要，这是我的代码。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

main()
{
//variables
FILE *rFile; 
int num_states;                 //number of states
int num_alphabet;               //number of alphabets
int num_acstates;               //number of accepting states
int ac_state;                   //the accepting state
char alphabet[num_alphabet];    //alphabet
char read_string[25];   //assuming the input will be maximum of 25 character
char input[25];
int i,j,x;                      //indexes for the loop


//open the file to read
rFile = fopen("dfa11", "r");

if (rFile != NULL)
{
    //do the program here

    //read number of states and number of alphabets
    fscanf(rFile, "%d %d", &num_states, &num_alphabet);

    //read the alphabet
    fscanf(rFile, "%s", &alphabet); 

    //read the state transition table (matrix)
    int value = num_states*num_alphabet;
    char table[num_states][num_alphabet];

    for(i=0; i<num_states; i++)
    {
        for(j=0; j<num_alphabet; j++)
        {
            fscanf(rFile, "%d", &table[i][j]);
        }
    }

    //read number of accepting states and accepting state
    fscanf(rFile, "%d", &num_acstates);
    fscanf(rFile, "%d", &ac_state);

    //read the input string from the file
    fscanf(rFile, "%s", &read_string);

    for(i=0; i<25; i++)
    {
        if (read_string[i] == '.')
            break;
        else
            input[i] = read_string[i];
    }

    //strncpy(input, read_string, j);

    printf("%d\n", strlen(read_string));
    printf("%d\n", strlen(input));
    printf("%s\n", read_string);
    printf("%s\n", input);


    //close the file
    fclose(rFile);
}

else
{
    printf("File could not be found");
}
}
4

2 回答 2

4

Im reading from a file and saving it into the char array as a string but when i try using stelen on the string, it crashes with a segmentation fault.

You don't need to take the address of read_string in fscanf, because read_string decays already to a pointer. Anyway, since &read_string == read_string in the case of an array (except for types), it shouldn't cause segmentation fault.

Therefore the problem comes from elsewhere. Among other, check that the line in your file is not larger than 25 characters.

Another problem is when i copy contents of read_string into another char array, it adds radom characters at the end.

Don't forget to add a '\0' at the end of your string.

input[i] = '\0';
于 2013-01-19T18:55:31.480 回答
0

尝试

fscanf(file, "%24s", read_string);

如果您的崩溃不再重现，则意味着您的文件包含超过 24 个字符的行。在这种情况下，您可以使缓冲区更大以避免此问题

编辑：

尝试input[i] = '\0';在for循环之后添加

for(i=0; i<25; i++)
{
    if (read_string[i] == '.')
        break;
    else
        input[i] = read_string[i];
}
input[i] = '\0';
于 2013-01-19T19:16:29.037 回答