C语言符号-取余\取模运算

int main() 
{ 
    //本质是向0取整 
    int i = -2.9; 
    int j = 2.9; 
    printf("%d\n", i); //结果是：-2 
    printf("%d\n", j); //结果是：2
    return 0; 
}

#include <stdio.h> 
#include <math.h> //使用了trunc函数，需要添加该头文件 
int main() 
{ 
    //本质是向0取整，注意输出格式
    printf("%.1f\n", trunc(-2.9)); //-2
    printf("%.1f\n", trunc(-2.1)); //-2 
    printf("%.1f\n", trunc(2.9)); //2 
    printf("%.1f\n", trunc(2.1)); //2
    return 0; 
}

#include <stdio.h> 
#include <math.h> //因为使用了floor函数，需要添加该头文件 
int main() 
{ 
    //本质是向-∞取整，注意输出格式
    printf("%.1f\n", floor(-2.9)); //-3 
    printf("%.1f\n", floor(-2.1)); //-3 
    printf("%.1f\n", floor(2.9)); //2 
    printf("%.1f\n", floor(2.1)); //2
    return 0; 
}

#include <stdio.h> 
#include <math.h>
int main() 
{ 
    //本质是向+∞取整，注意输出格式
    printf("%.1f\n", ceil(-2.1)); //-2 
    printf("%.1f\n", ceil(2.9));  //3 
    printf("%.1f\n", ceil(2.1));  //3 
    return 0; 
}

#include <stdio.h> 
#include <math.h>
int main() 
{ 
    //本质是四舍五入，同样注意输出格式
    printf("%.1f\n", round(2.1)); 
    printf("%.1f\n", round(2.9)); 
    printf("%.1f\n", round(-2.1)); 
    printf("%.1f\n", round(-2.9));
    return 0; 
}

#include <stdio.h> 
#include <math.h> 
int main() 
{ 
    const char * format = "%.1f \t%.1f \t%.1f \t%.1f \t%.1f\n";                       printf("value\tround\tfloor\tceil\ttrunc\n"); 
    printf("-----\t-----\t-----\t----\t-----\n"); 
    printf(format, 2.3, round(2.3), floor(2.3), ceil(2.3), trunc(2.3)); 
    printf(format, 3.8, round(3.8), floor(3.8), ceil(3.8), trunc(3.8)); 
    printf(format, 5.5, round(5.5), floor(5.5), ceil(5.5), trunc(5.5)); 
    printf(format, -2.3, round(-2.3), floor(-2.3), ceil(-2.3), trunc(-2.3)); 
    printf(format, -3.8, round(-3.8), floor(-3.8), ceil(-3.8), trunc(-3.8)); 
    printf(format, -5.5, round(-5.5), floor(-5.5), ceil(-5.5), trunc(-5.5));
    return 0; 
}

int main() 
{ 
    int a = 10; 
    int d = 3; 
    printf("%d\n", a%d); //结果是1 （c，python结果相同）
    //因为：a=10,d=3,q=3,r=1 0<=r<d(3) 
    //所以：a = q*d+r -> 10=3*3+1 
    return 0; 
}

int main() 
{ 
    int a = -10; 
    int d = 3;
    printf("%d\n", a/d); //C语言中是-3，python是-4
    printf("%d\n", a%d);//C语言中是-1，python是2
    return 0; 
}