“x=4+5”“x=x-1”是某一程序中的前后相邻两个语句,那么下列说法

“x=4+5”“x=x-1”是某一程序中的前后相邻两个语句,那么下列说法正确的是(    )

①x=4+5的意思是x=4+5=9,此式与算术中的式子是一样的  ②x=4+5是将数值9赋给x  ③x=4+5可以写成4+5=x  ④x=x-1语句在执行时,“=”右边x的值是9,执行后左边x的值是8

A.①③                  B.②④                  C.①④                  D.②③

答案

答案:

B

思路分析:

①x=4+5的意思是将9赋值给x;③赋值语句中“=”左右两边不能互换,即不能给常量赋值.左边必须是变量,右边必须是表达式.故①③错误.

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