c - 带嵌套If的C代码For循环；模数和平方根问题

所以，我试着让C代码工作。它编译，但产生不正确的输出。它应该列出1到选定值之间的所有pefect平方数。
它做了一些错误的事情，经过一系列的尝试和错误，我认为问题在于模运算…比如它的提前截断或者做一些其他奇怪的事情。

// C Code


/*This program will identify all square numbers between one and a chosen integer*/

#include <stdio.h>
#include <math.h>

int main(){

int i, upper, square_int;
float square;
printf("This program will identify all square numbers between one and a chosen integer");

printf("Please enter the upper limit integer:");
scanf("%d", &upper);

upper = 13; /*scanf is the primary integer input method; this is here just to test it on codepad*/

for (i = 1; i<= upper; ++i) /*i want to run through all integers between 1 and the value of upper*/
{
    square = sqrt(i);  /* calc square root for each value of i */
    square_int = square;  /* change the root from float to int type*/

    if (i % (int)square_int == 0) /*check if i divided by root leaves no remainder*/
        printf("%d\n", i);  /*print 'em*/
}
printf("This completes the list of perfect squares between 1 and %d",upper);

return 0; /*End program*/
}

codepad上的输出是：

This program will identify all square numbers between one and a chosen integerPlease enter the upper limit integer:1
2
3
4
6
8
9
12
This completes the list of perfect squares between 1 and 13

这当然是错的。我希望能得到1，2，4和9。有人能指出我在这里的坏处吗？

最佳答案

这里有一个简单的算法

int i = 1;
while (i*i < upper)
{
    printf("%d\n", i*i);
    ++i;
}

另一种方法是计算平方根，将其转换为int，然后比较数字。

for (i = 1; i <= upper; ++i)
{
    square = sqrt(i);
    square_int = square;
    if (square == (float)square_int)
        printf("%d\n", i );
}

关于c - 带嵌套If的C代码For循环；模数和平方根问题，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/29283657/