有没有办法在 C 文件中找到特殊字符 '\n' 的位置？

Question

我想在一个文件中找到'\n'的位置，并打印出\n之后剩余的字符

我尝试使用 lseek 查找“\n”出现的次数，但我似乎无法找到特殊字符“\n”出现的位置

我也试过使用 strok 来分解特定文件并使用 lseek 来找到最后一个字符的位置

#define MAX_BUFFER_LENGTH 512
//path name is the file that is being accessed
void printLines(char *initPathName, char *initBuffer, int initnumberRead)
{   
int fileDescriptor; 
int numOfBreaks =0;

char *pathName=initPathName;
fileDescriptor = open(pathName, O_RDONLY);

lseek(fileDescriptor,initnumberRead * -1, SEEK_END); 

int size =  read(fileDescriptor, initBuffer, MAX_BUFFER_LENGTH);
initBuffer[size] = '[=10=]';
char *token = strtok(initBuffer, "\\n\r"); 

for(int i= 0;token !=NULL;i++)
{
    write(2,token, strlen(token));
    write(2,"\n", 2);
            write(2,"a break occured\n", 17);
    token = strtok(NULL,"\\n\r"); 
}
close(fileDescriptor);
}

输入

./program some.txt -l 3 // this prints the number of lines to be printed and separated with line breaks

应该做什么

打印三行

some text 
a break occured
some text 
a break occured
some text 
a break occured

输出

相反，它会打印文件中的字符数并根据 \n 出现的时间对其进行格式化

.. ext 
a break occured

Answer 1

I want to find the position of a '\n' in a file and print out the remaining characters after \n

#include <stdio.h>

long long find_first_newline_then_print(FILE *fn) {
  int ch;
  long long pos = 0;
  while ((ch = fgetc(fin)) != EOF && ch != '\n') ++pos;
  if (ch == EOF) return -1;
  while ((ch = fgetc(fin)) != EOF) fputc(ch, stdout);
  return pos + 1;
}

有没有办法在 C 文件中找到特殊字符 '\n' 的位置？

Is there a way to find the position of a special character '\n' in a file in C?

c

lseek

输入

应该做什么

输出