我有一个程序应该计算 txt 文件中的字符并使用子进程来计算字符然后打印出数量。父母只是在一个while循环中将文件中的行提供给孩子。该程序的工作原理是它可以打开文件，逐行读取它，然后如果子进程打印出正确的数量。
但是现在我想修改它，以便子进程将金额传回，而父进程则写出 nr 的字符。但是当我尝试这样做时，程序给了我 1153416175 而不是文件中的实际字符数，而且它只是卡住了，我必须杀死它。为什么会这样？
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#define MAXLINE 100
int main(int argc, char *argv[]) {
int fds[2]; /* file descriptors */
int child; /* child process */
int n; /* size of line in file */
int count, alphacount, total=0; /* used in loop for counting chars in line */
int read_bytes; /* amount of bytes read in read function */
char line[MAXLINE];
FILE *fp;
char *str;
if (argc < 2) {
printf("Format: './rakna <filename>'.\nThe file should have the .txt extension.\n");
exit(1);
} else {
if (pipe(fds) < 0) {
perror("Can't open pipe\n");
exit(1);
}
child = fork();
if (child==-1) {
perror("fork error");
exit(1);
}
/* child that reads chars and returns amount */
if(child == 0)
{
/* close(fds[1]); child process close input of pipe Used to be before ..*/
/* count chars through read */
while (read_bytes = read(fds[0], line, sizeof(line)) > 0) {
/* check if line is received */
if (read_bytes < 0) {
perror("Can't read line");
exit(1);
}
/* count chars in the line */
else {
count=0;
alphacount=0;
while (line[count] != '\0')
{
/* counting chars from 'a' to 'z' */
if (line[count] >= 'a' && line[count] <= 'z')
alphacount++;
/* counting chars from 'A' to 'Z' */
else if (line[count] >= 'A' && line[count] <= 'Z')
alphacount++;
count++;
}
/* adding the nr of chars in line to total */
total += alphacount;
}
}
write(fds[1], &total, sizeof(total)); /* passing total nr of chars to parent */
close(fds[0]); /* closing output part of pipe */
exit(0); /* ending child process */
}
/* parent that sends chars to child-reader and writes out amount */
else
{
/* close(fds[0]); Parent process close output of pipe */
fp = fopen(argv[1], "r");
if (fp == 0) {
perror("Could not read the file.\n");
exit(1);
}
while (fgets(line, MAXLINE, fp) != NULL) {
n = strlen(line);
if (n >= 0) {
line[n]='\0';
if (write(fds[1], line, n) != n) {
perror("write error in pipe");
exit(1);
}
}
else {
perror("problem with fgets");
exit(1);
}
}
int nrofchars;
read_bytes = read(fds[0], &nrofchars, sizeof(nrofchars));
printf("The file has %d nr of chars between a-z\n", nrofchars); //<-- Here it f**ks up, it gives me 1153416175
close(fds[1]); /* closing input part of pipe */
wait(NULL); /* waits for child to read end of file */
}
return 0;
}
}