Question

我想读取文件的内容并打印其内容的反面。仅使用fopen，fgets，fputs，fclose。这是我所做的，但是什么也没打印。

string s = "23031"; 

    stringstream test(s);
    int x = 0; 
    test>> x; 

    // Now the variable x holds the value 23031
    cout << "Value of x : " << x;

输出：

#include <sys/types.h>                                                          
#include <sys/stat.h>                                                           
#include <sys/fcntl.h>                                                          
#include <unistd.h>                                                             
#include <stdio.h>                                                              

int main(int argc, char *argv[])                                                
{                                                                               
    if (argc != 2)                                                              
    {                                                                           
        return 1;                                                               
    }                                                                           
    FILE *f = fopen(argv[1], "r");                                              
    if (f == NULL)                                                              
    {                                                                           
        return 2;                                                               
    }                                                                           
    char buffer[4096];                                                          
    char reversed[4096];                                                        
    char *line = fgets(buffer, 50, f); //read 50 characters at a time                                   
    int length = 0;                                                             
    int j = 0;                                                                  
    while (line != NULL)        // while end of file not reached                                                 
    {                                                                           
        length = 0;                                                             
        j = 0;                                                                  
        for (char *temp = buffer; *temp != '\0'; temp++)    //find length of buffer                 
        {                                                                       
            length += 1;                                                        
        }                                                                       
        for (int i = length; i > 0; i--)          // reverse buffer                              
        {                                                                       
            reversed[j] = buffer[i];                                            
            j += 1;                                                             
        }                                                                       
        fputs(reversed, stdout);                                                
        line = fgets(buffer, 50, f);                                            
    }                                                                           
    fclose(f);                                                                  
    return 0;                                                                   
}

示例：

(nothing)

预期输出：

abcdef
ghi

Answer 1

您从错误的偏移量开始

for (int i = length; i > 0; i--)          // reverse buffer

切换到

for (int i = length - 1; i >= 0; i--)    // reverse buffer

否则，您交换/反转NUL终止符并得到一个空字符串

C-将反转的文件内容打印到stdout

1 个答案: