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所以我们必须创建一个程序来创建3个子进程，它们将信息彼此传递。有人可以帮我完成管道上的任务吗？
- 第一个进程从文件读入数据。
- 第二个过程通过转换每个字母上的上限（即小写字母转换为大写字母，反之亦然）来更改该数据。
- 第三个进程将信息写入文件。
我的问题是，我似乎无法使用fork()和waitpid()来运行进程。对于waitpid()，我真的不知道第二和第三个参数属于什么。这是我的主：
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "pipe.c"
int main(void) {
int p, p2, rc, rc2;
rc = _pipe(f_des);
rc2 = _pipe(C1C2);
pid_t pid[3];
pid[0] = fork();
if (pid[0] == 0) {
puts("create child 1");
do_child0();
exit(0);
}
pid[1] = fork();
if (pid[1] == 0) {
puts("create child 2");
do_child1();
exit(0);
}
pid[2] = fork();
if (pid[2] == 0) {
puts("create child 3");
do_child2();
exit(0);
}
waitpid(pid[0], NULL, 0);
waitpid(pid[1], NULL, 0);
waitpid(pid[2], NULL, -1);
printf("children done, parent goes");
return 0;
}
pipe.c：
#include "pipe.h"
void do_child1() {
int c, p2;
int rc, rc2;
char *line2, *line3;
int i = 0;
int j = 0;
int k = 0;
char buffer[80];
//char *line;
close(f_des[1]);
close(C1C2[0]);
printf("Received by child 2 from child 1: ");
while(k<26) {
for (i = 0; i <= 40; i++) {
if ((read(f_des[0], buffer, 1)) != '\0') {
//while((rc = read(f_des[0], buffer, 40))) {
printf("%s", buffer);
j = 0;
line2 = (char *)malloc(sizeof(char)*40);
read(f_des[0], buffer, 40);
line2 = buffer;
line3 = (char *)malloc(sizeof(char)*40);
line2 = line3;
rc = read(f_des[0], line2, 40);
printf("%s\n",line2);
while(j < 40) {
if(islower(*(line3+j)))
*(line3+j) = toupper(*(line3+j));
if(isupper(*(line2+j)))
*(line3+j) = tolower(*(line3+j));
}
rc2 = write(C1C2[1], line3, 40);
printf("\nLine 3: %s", line3);
k++;
}
}
}
printf("\n");
close(C1C2[1]);
close(f_des[0]);
exit(0);
}
void do_child2() {
int c;
int rc;
char *line4;
close(C1C2[1]);
while((rc= read(C1C2[0], line4, 40)>0)) {
line4 = (char*)malloc(sizeof(char)*40);
printf("%s\n", line4);
}
FILE *file;
file = fopen("C:\\Users\\apkim_000\\Desktop\\newReluctance.c", "a+");
fprintf(file, "%s", line4);
fclose(file);
}
void do_child0() {
FILE *inf = fopen("C:\\MinGW\\bin\\Reluctance.c", "r");
int c;
int rc;
int i =0;
char buffer[80];
char *line;
cntr = 0;
close(f_des[0]);
printf("From child 1: \n");
while (1) {
fgets(buffer, 100, inf); //reads in at most 80 char from a line
if (feof(inf)) //this checks to see if the special EOF was read
break; //if so, break out of while and continue with your main
line = (char*)malloc(sizeof(char)*40);
line = strtok(buffer, "\n");
printf("%s\n", line);
i++;
cntr++;
write(f_des[1], buffer, 40);
}
close(f_des[1]);
exit(0);
}
pipe.h：
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
void do_child1();
void do_child2();
void do_child0();
int f_des[2];
int C1C2[2];
int cntr, p3;
编译器输出：
create child 1
From child 1:
Reluctance
OUT through the fields and the woods
And over the walls I have wended;
I have climbed the hills of view
And looked at the world, and descended;
I have come by the highway home,
And lo, it is ended.
The leaves are all dead on the ground,
Save those that the oak is keeping
To ravel them one by one
And let them go scraping and creeping
Out over the crusted snow,
When others are sleeping.
And the dead leaves lie huddled and still,
No longer blown hither and thither;
The last lone aster is gone;
The flowers of the witch-hazel wither;
The heart is still aching to seek,
But the feet question 'Whither?'
Ah, when to the heart of man
Was it ever less than a treason
To go with the drift of things,
To yield with a grace to reason,
And bow and accept the end
create child 2
Received by child 2 from child 1: RUT through the fields and the woods
create child 3