用C创建一个可在Linux基本系统上运行的数字秒表程序。
keyboardhit()函数只是代表键盘点击。按下键后,它将生成信号并返回非零整数。其中有4个循环,第一个循环持续数小时,第二个循环持续数分钟,第3个持续秒数,第4个循环保持秒数的速度(3个循环)。运行该程序后,它等待键盘启动键被按下,当按下该键时,它会产生一个信号。为了存储键盘键,有一个变量(c),如果c等于p键,则它调用wait函数。该线程在后台运行,我们正在等待按下开始键。按下s键后,线程再次跳至thread_join函数,如果按下r键,则跳入复位标签,所有循环再次从零开始,如果按下s键,则跳入开始标签,如果e键为按下它会调用exit()函数,程序将终止。
先决条件: c中的线程,等待系统调用
要执行该程序,我们使用以下命令:
输入:按一个键:s->开始e->退出r->重置p->暂停输出:
// C code to create stop watch
// Header file for necessary system library
#include
#include
#include
#include
#include
#include
// starting from zero
#define MIN 0
// 1 hr= 60 min ; 1 min= 60 sec
#define MAX 60
#define MILLI 200000
int i, j, k, n, s;
char c;
pthread_t t1;
// Function to perform operations
// according keyboeard hit.
int keyboardhit(void)
{
struct termios oldt, newt;
int ch;
int oldf;
tcgetattr(STDIN_FILENO, &oldt);
newt = oldt;
newt.c_lflag &= ~(ICANON | ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &newt);
oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
ch = getchar();
tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
fcntl(STDIN_FILENO, F_SETFL, oldf);
if (ch != EOF) {
ungetc(ch, stdin);
return 1;
}
return 0;
}
// display stopwatch on screen
void print()
{
// clear screen escape sequence
printf("\033[2J\033[1;1H");
// Display Hour Min Sec in screen
printf("TIME\t\t\t\tHr: %d Min: %d Sec: %d", n, i, j);
}
// function to pause stopwatch
void* wait(void* arg)
{
while (1) {
// wait for keyboard signal if keyboard
// hit it return non integer number
if (keyboardhit()) {
// take input from user and do
// operation accordingly
c = getchar();
if (c == 'S' || c == 's') {
break;
}
else if (c == 'r' || c == 'R') {
s = 1;
break;
}
else if (c == 'e' || c == 'E')
exit(0);
}
}
}
// driver code
int main()
{
// label to reset the value
reset:
n = MIN;
i = MIN;
j = MIN;
k = MIN, s = MIN;
print();
while (1) {
/* s for start
e for exit
p for pause
r for reset
*/
if (keyboardhit()) {
c = getchar();
if (c != 's')
continue;
for (n = MIN; n < MAX; n++) {
for (i = MIN; i < MAX; i++) {
for (j = MIN; j < MAX; j++) {
for (k = MIN; k < MILLI; k++) {
start:
print();
if (keyboardhit()) {
c = getchar();
if (c == 'r' || c == 'R')
goto reset;
else if (c == 'e' || c == 'E')
exit(0);
else if (c == 's' || c == 'S')
goto start;
else if (c == 'P' || c == 'p') {
pthread_create(&t1, NULL, &wait, NULL);
// waiting for join a thread
pthread_join(t1, NULL);
if (s == 1)
goto reset;
}
}
}
}
}
}
}
}
return 0;
}
输出:
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