“fork()”之后的printf異常操作系統(tǒng)：Linux，語言：純C我正在學(xué)習(xí)一般的C編程，以及UNIX下的特殊情況下的C編程。我發(fā)現(xiàn)了一種奇怪的行為printf()函數(shù)在使用fork()打電話。電碼#include <stdio.h>#include <system.h>int main(){
int pid;
printf( "Hello, my pid is %d", getpid() );
pid = fork();
if( pid == 0 )
{
printf( "\nI was forked! :D" );
sleep( 3 );
}
else
{
waitpid( pid, NULL, 0 );
printf( "\n%d was forked!", pid );
}
return 0;}輸出量Hello, my pid is 1111I was forked! :DHello, my pid is 11112222 was forked!為什么第二個(gè)“Hello”字符串出現(xiàn)在子程序的輸出中？是的，這正是父母在開始時(shí)打印的，父母的pid.但!如果我們把\n字符在每個(gè)字符串的末尾，我們得到預(yù)期的輸出：#include <stdio.h>#include <system.h>int main(){
int pid;
printf( "Hello, my pid is %d\n", getpid() ); // SIC!!
pid = fork();
if( pid == 0 )
{
printf( "I was forked! :D" ); // removed the '\n', no matter
sleep( 3 );
}
else
{
waitpid( pid, NULL, 0 );
printf( "\n%d was forked!", pid );
}
return 0;}輸出量:Hello, my pid is 1111I was forked! :D2222 was forked!為什么會(huì)發(fā)生這種事？它是正確的行為，還是一個(gè)錯(cuò)誤？
“fork()”之后的printf異常
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2019-06-01 16:23:58
