_循环loop.pptVIP

内容回顾-Selection 1 if Statement if (expression) { statement1; statement2; } 2 if - else Statement if (expression) { statement1; statement2; } else { statement3; statement4; } 3. if – else - if Statement if (expression) statement; else if (expression) statement; else if (expression) statement; else statement; 4. if statement that contains other if / if - else statements if (age 18) { if (age 55) price = 2.50; /* Price for senior citizens */ else price = 5.00; /* Price for adults */ } else { if (age 1) price = 0.0; /* Price for infants */ else price = 1.50; /* for children teenagers*/ } 5. switch and break switch (month) { case 1: printf(“January\n”); break; case 2: printf(“February\n”); break; case 3: printf(“March\n”); break; default: printf(“Others\n”); break; } printf(“End”); 思考题Exercise： 例1 考虑下面程序输出结果: main() { int x=100,a=10,b=20; int v1=5,v2=0; if(ab) if(b!=15) if(!v1) x=1; else if(v2) x=10; x=-1; printf(“%d”,x); } 思考题Exercise:： 例2 考虑下面程序输出结果: { int x=1,y=0,a=0,b=0; switch(x) { case 1: switch(y) { case 0: a++; break; case 1: b++; break; } case 2: a++;b++; break; case 3: a++;b++; } printf(“\na=%d,b=%d”,a,b); } if ~ else 配对原则：缺省{ }时，else总是和它上面离它最近的未配对的if配对 第5章 本章要点 循环的基本概念 不同形式的循环控制 多重循环问题 主要内容 5.1 概述 5.2 用while语句实现循环 5.3 用do-while语句实现循环 5.4 用for 语句实现循环 5.5 循环的嵌套 5.6 几种循环的比较 5.7 break语句和continue语句 5.8 程 序 举 例 §5.1 概述 Loop Structure if –goto while do while for §5.2 用while语句实现循环Condition is tested first Count Controlled例5.2 求1到100的和#include