C语言编程学习课件 (13).pdf

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1、Programming In CProgramming In C Programming In CProgramming In C In C programs,we often encountered that after variable calculation,the value itself needs to be increased by 1 or decreased by 1.For example,counters,loop control variables,character pointers,the values of them are needed to adjust af

2、ter each operation.In C,two operators are provided,which can concisely and efficiently complete other operations while realize the increase and decrease of the variable itself.This is the increment operation.Programming In CProgramming In C There are two kinds of incremental operators:increment and

3、decrement：+、-They are all unary operations with a high precedence.They are second only to operators with precedence of 1 such as parentheses.They are the same as positive and negative operations and higher than other arithmetic operations.The association of the increment operator is from right to le

4、ft.The increment operation can only be used before or after the variable name.It can realize increment and decrement for various basic variables or pointer variables.Programming In CProgramming In C The increment operations have two forms:prefix and postfix.The operators before variables are called

5、prefixes.It is to increase or decrease the variable first,and then take the value after the increment and decrement to participate in the expression operation.The operators after variables are called postfixes.It is to take the original value of the variable to participate in the expression operatio

6、n,and then the value of the variable increases or decreases.It can be seen that both the prefix and postfix,they are the same to the increment or decrement of the variable itself.They influence the result of the expression.Programming In CProgramming In C#include int main(void)int i,j=5;i=+j;printf(

7、i=%d,j=%dn,i,j);j=5;i=j+;printf(i=%d,j=%dn,i,j);return 0;The result is i=6,j=6 i=5,j=6 “i=+j”equivalent to:1.j+;2.i=j;“i=j+”equivalent to:1.i=j;2.j+;Programming In CProgramming In C#include stdio.h main()int s=65,n=1,t;t=+s+n+;printf(s=%c,t=%cn,s,t);t=+s*-n%s;printf(s=%d,t=%dn,s,t);Program output s=

8、B,t=C s=67,t=0 The Comma Operator x=(y=3,y+1);first assigns y the value 3 and then assigns x the value 4.The parentheses are necessary because the comma operator has a lower precedence than the assignment operator.The comma expressions are operated from left to right one by one.The value of the entire expression is the value of the last expression.i=1,j=0i=1,j=0，x=a=3,6*3x=a=3,6*3 x/(y+1),a+b,3*4x/(y+1),a+b,3*4 18 int a,b,c,d;int a,b,c,d;d=(a=10,b=20,c=30,+a+b+c);d=(a=10,b=20,c=30,+a+b+c);Programming In CProgramming In C