Question

有没有办法浏览文件，可以选择上下移动行号而不是顺序？

截至目前，我的代码使用fgets来获取文件中的最后一行ascii字符，但通过我的研究，我还没有找到一种更智能的方法来遍历文件。

例如：

file.txt contains:

"hello\n"
"what's up?\n"
"bye"

我需要能够返回＆＃34; bye＆＃34;首先，然后使用按键，打印＆＃34;什么是＆＃34;然后再回到＆＃34; bye＆＃34;通过另一个按键。

Answer 1

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

int main()
{
    FILE *infile;
    char *infile_contents;
    unsigned int infile_size;

    // to read all of the file
    infile = fopen("file.txt", "rb");
    fseek(infile, 0, SEEK_END);
    infile_size = ftell(infile);
    fseek(infile, 0,SEEK_SET);
    infile_contents = malloc(infile_size+1);
    fread(infile_contents, infile_size, 1, infile);
    fclose(infile);
    infile_contents[infile_size]=0;

    // to store the beginning of lines and replace '\n' with '\0'
    size_t num_lines = 1, current_line = 1, length;
    char **lines = malloc(sizeof(char*)), **lines1, *tmp;
    lines[0] = infile_contents;
    while(tmp = strchr(infile_contents, '\n'))
    {
        // to resize lines if it is not big enough
        if(num_lines == current_line)
        {
            lines1 = lines;
            lines = malloc((num_lines<<1)*sizeof(char*));
            memcpy(lines, lines1, num_lines*sizeof(char*));
            memset(lines+num_lines, 0, num_lines*sizeof(char*));
            num_lines <<= 1;
            free(lines1);
        }

        *tmp=0;
        infile_contents = tmp+1;
        lines[current_line++] = infile_contents;
    }

    // to print the lines
    num_lines = current_line-1;
    current_line = num_lines;

    // to skip the last line if it is empty
    if(!lines[current_line][0])
    {
        num_lines--;
        current_line = num_lines;
    }

    while(1)
    {
        printf("%s",lines[current_line]);
        if(getchar())// change to the condition for going down
        {
            if(current_line)
                current_line--;
            else
                current_line=num_lines;
        }
        else
        {
            if(current_line==num_lines)
                current_line=0;
            else
                current_line++;
        }
    }
}

浏览文件行 - C.

1 个答案: