C语言while、do-while、for循环课程5
课程3中,提到C语言基本语句分为:数据定义语句,数据处理语句
数据处理语句又可分为:表达式语句,函数调用语句,空语句(;,复合语句,流程控制语句。
流程控制:指程序代码执行的顺序。流程的分类:顺序、选择、循环。
C语言的循环结构通过三种语句来实现,即while、do-while、forWhile语句的一般形式while(循环条件表达式循环体语句;
功能:当循环条件表达式为真,执行循环体语句,执行完了,再判断条件表达式是否为真,为真,则再执行,直到条件表达式为假时,退出while循环。
实例1:用while语句求1~100的累加和。
#include//C语言编译预处理命令,文件包含为stdio.h
voidmain(//至少有一个用main(命名的主函数,返回值为void无值类型{
inti=1,sum=0;/*初始化循环,定义变量i和累加器sum,定义和之前,累加器清零*/
while(i<=100
{
sum+=i;//sum+=i是一个复合赋值运算符,等价于sun=sun+i;i++;
}
printf("1+2+3+...+100=%d ",sum;//输出十进制数,1加到100累加器的和}
MicrosoftVisualC++6.0运行结果
使用while循环时,一定要对循环条件表达式中出现的变量提前赋值,并在循环体内修改有关变量的值,以使循环能趋于终止。
While循环为当型循环,do-while循环也叫直到型循环。
do-while语句的一般形式为:
do
{
循环体语句}while(
循环条件表达式
实例2:用do-while编制一个求n!的程序,n的值由键盘输入。
#include
voidmain(
{inti=1,n,p=1;
printf("请从键盘输入一个数,进行连乘积: ";
scanf("%d",&n;
do
{p=p*i;
i++;
}while(i<=n;
printf("连乘积的结果为p=n!:%d ",p;
}
分析:此程序,先定义三个变量i、n、p,p从p乘1开始执行,再i进行自增1,循环体中的语句执行完毕后,判断while的循环条件表达式,当i自增1为2时,看2是否<=输入的n值,若为真,则继续返回do循环,直到i自增的值比n大,则退出循环。
do-while主要用于人机交互,do-while循环是先执行后判断,do里面的循环体至少被执行一次。区别于while是先判断循环条件表达式,后执行。
for循环也叫步长型循环
一般格式:for(表达式1;表达式2;表达式3循环体语句;
功能:先执行表达式1,再执行表达式2,如果表达式2的值为真,就执行循环体语句,最后执行表达式3.完成一次循环后,从表达式2执行,直到表达式2为假,退出循环。
实例3:参考实例1,用while求1~100的累加和,现在用for语句求1~100的累
加和。
#include
intmain(void
{
inti;intsum=0;
/*初始化循环,定义变量i
和累加器sum,定义和之前,累加器清零*/
for(i=1;i<=100;i++
{
sum=sum+i;
}
printf("sum=%d ",sum;
return0;
}
实例4:爱因斯坦的`阶梯问题:有一个长阶梯,若每步上2阶,最后剩1阶;若每步上3阶,最后剩2阶;若每步上5阶,最后剩4阶;若每步上6阶,最后剩5阶;只有每步上7阶,最后刚好一阶也不剩。请问该阶梯至少有多少阶。编写一个C程序解决该问题。
#include
main(
{intx;
for(x=7;;x+=7
if(x%3==2&&x%5==4&&x%6==5
break;
printf("Thenumberoftheladdersis:%d ",x;
}
分析:发现x一定是7的整数倍,可以依次递增地求出7的整数倍的值(7*1、7*2、7*3……),每求出一值,就用该值与2、3、5、6进行取模运算,最先得到的满足上述5个方程式的x值即为本题的答案。
用while语句,简单快速实现爱因斯坦的阶梯问题
#include
intmain(
{
inti=1;/*i为所设的阶梯数*/
while(!((i%2==1&&(i%3==2&&(i%5==4&&(i%6==5&&(i%7==0
++i;/*满足一组同余式的判别*/
The start of this year's first class show strong,unusually brilliant.China's first female astronaut liu Yang first appeared as a guest speaker,she spoke about full of poetry,vivid tells the story of the beauty of the space,the beauty of the earth,at the same time also tells the story after she returned to the earth the beauty of human nature,tender feeling and touching.
Said liu himself in the space,more was shocked by the beauty of the earth,"this generation inhabit our planet,in the boundless universe should appear so magnificent,so dazzling,she segmental arc edge is visible,covered with a layer of blue and white halo,sunlight cast in the sea deep shallow blue,vein and clear,clear long coastline.The earth is so beautiful,exquisite planet,in a dark universe,quietly coruscate gives a dreamy,blue light,like a Mosaic on the black velvet of the sapphire,it is a kind of beyond the beauty of language.It is my home,where are my dearest friends and family,at that moment,I was so far away from the earth,but it is so close to".
Liu Yang can't wait to return to the bosom of the earth in space,"after such a trip to space,saw the smallness of the earth,to better understand the earth's greatest; left earth,and realize the dependence on the planet is infinite,infinite love.I love the sunshine here,love the fresh air here,love the pure water here,love the rivers and lakes here,love the mountains,plains,love live here diverse species,love living here we human beings".
The most beautiful,brought color to our life,warm every hurt heart,healing,gives people hope,the future and courage,they are the most beautiful,is also the most lovely!
Yesterday I saw the school first class, feeling very deep. This year's theme is beauty is near. Beauty, a very common words, we are literally think beauty is beautiful. So, what is the true meaning of beauty?
With the question I look up, the first lesson is to find beauty. How to find? It makes people lost in thought. When everybody zhang two monks confused, host "shenzhou" 9 astronaut liu Yang, please tell for you. Liu said, the universe is endless, much bigger than she had expected: long, on the other side of the galaxy, the star vega, mercury, Saturn... . All panoramic view. Time is the most interesting of weightlessness, everyone one by one all floating in the air, pens, book ah of what are messy, can be fun. Finally, she concludes the essence to find beauty, love sports, and more to find the beauty around, so beauty will show in front of you.
LiuLiLi mountain elementary school teachers as the second class of the bell took to the podium, she is only 20 years old this year, in this flower age, many girls are enjoying, who will suffer poor mountainous areas! Can't liu, she is out of the mountain, liu with great love for the children's happiness, she hold the children art, gymnastics and other mountainous area children can't learn knowledge. Liu planted beauty, transfer the beauty. Let the beauty of the mountains germination, results. So she right because when people called the most beautiful teacher, this is to create beautiful?
Gymnastics team player Chen yibing showed also in the field. His contribution for our country in the London Olympic Games, the host asked him why he is going to win? His answer: before the race, they are seen as a failure. But because of his companions support each other, encourage each other. Make them very first champions league. The companion's encouragement is beauty.
Yu Dan is the most let me have a feeling of the teacher's words. She hit a harmonious beauty, for example, put eggs, tea, carrot in boiling water, eggs, hardened into the fragrant tea, tea radish was soft. That means what? Hardened eggs tend to be the kind of person who are "really low on agreeableness, and most men are single minded and turnip are too weak, they couldn't get hold of degree dating, so don't be understood, so being bullied. And the tea? It combines with water, this kind of person is good at unity collective, so they are best represents the harmonious beauty.
The school first class with only an hour and a half, but let me benefit a lot.
© 2022 xuexicn.net,All Rights Reserved.