感悟

int i = (int)(a/10.0 + 0.5)*10;
    int j = (int)(a + 0.5);
    float b = (int)((a * 100) + 0.5)/100.0;
    printf("i = %d\n",i);//个位四舍五入
    printf("j= %d\n",j);//四舍五入成整型
    printf("b = %0.2f\n",b);//保留两位小数