关于求绝对值的问题

 

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当用abs求绝对值时，需要注意不同的数据类型调用不同的API函数，其中abs、labs、fabs分别对应整型、长整型、浮点型。假如对浮点数用了abs得到的将是强制转换后的整型。下面是MSDN上的例子：

Example

/* ABS.C: This program computes and displays * the absolute values of several numbers. */#include  <stdio.h>#include  <math.h>#include  <stdlib.h>void main( void ){   int    ix = -4, iy;   long   lx = -41567L, ly;   double dx = -3.141593, dy;   iy = abs( ix );   printf( "The absolute value of %d is %d/n", ix, iy);   ly = labs( lx );   printf( "The absolute value of %ld is %ld/n", lx, ly);   dy = fabs( dx );   printf( "The absolute value of %f is %f/n", dx, dy );}

Output

The absolute value of -4 is 4The absolute value of -41567 is 41567The absolute value of -3.141593 is 3.141593

 

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