#include <stdio.h>
#define NUM 20
int main(void)
{
    int i, j;
    for (i = 0; i < NUM; ++i)
    {
         for (j = 0; j <= i; ++j)
         {
             putchar('=');
         }
         for (j = i; j < NUM; ++j)
         {
             putchar(' ');
         }
         printf("%3d%%", (i + 1) * 100 / NUM);
         printf("\r");
         fflush(NULL);
         sleep(1);
    }
    return 0;
}

运行结果：
==========================                          52%

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