–

[Arithmetic Operators]

描述

Subtraction is one of the four primary arithmetic operations. The operator - (minus) operates on two operands to produce the difference of the second from the first.

語法

difference = operand1 - operand2;

參數

difference: variable. Allowed data types: int, float, double, byte, short, long.
operand1: variable or constant. Allowed data types: int, float, double, byte, short, long.
operand2: variable or constant. Allowed data types: int, float, double, byte, short, long.

範例程式碼

int a = 5;
int b = 10;
int c = 0;
c = a - b;  // the variable 'c' gets a value of -5 after this statement is executed

Tips

1. The subtraction operation can overflow if the result is smaller than that which can be stored in the data type (e.g. subtracting 1 from an integer with the value -32,768 gives 32,767).
2. If one of the numbers (operands) are of the type float or of type double, floating point math will be used for the calculation.
3. If the operands are of float / double data type and the variable that stores the difference is an integer, then only the integral part is stored and the fractional part of the number is lost.

float a = 5.5;
float b = 6.6;
int c = 0;
c = a - b;  // the variable 'c' stores a value of -1 only as opposed to the expected difference of -1.1

語法參考主頁面

86Duino 參考的文本是根據 Creative Commons Attribution-ShareAlike 3.0 License，部分文本是從 the Arduino reference 修改的。 參考中的代碼示例已發佈到公共領域。