【C语言学习】《C Primer Plus》第7章 C控制语句：分支与跳转

学习总结

1、if…else…从语义上看就能出用途，跟其他语言没差多少，只需要记住，世界上最遥远的距离之一：我走if你却走else。

2、根据个人几年的编程经验，太多的if…else…嵌套会加大代码的可读性和维护难度。个人认为代码最好不要超过三层if…else…的嵌套，否则最好使用布尔值控制流程。

3、逻辑运算符优先级：!>&&>||

4、运行到continue语句将导致剩余的迭代部分被忽略，开始下一次迭代。continue仅用于循环，而break语句用于循环和switch中。

5、编程题（题1）：

 #include <stdio.h>

 int main(){
         int space=,newline=,other=;
         char ch;
         printf("please enter something:\n");
         while((ch=getchar())!='#'){
                 if(ch=='\n'){
                         newline+=;
                 }else if(ch==' '){
                         space+=;
                 }else{
                         other+=;
                 }
         }
         printf("space is %d\n",space);
         printf("newline is %d\n",newline);
         printf("other is %d\n",other);
         return ;
 }

运行结果：

please enter something:

hello world!

hi nihao.

#ABC

space is 2

newline is 2

other is 19

6、编程题（题11）：

 #include <stdio.h>
 #define ARTICHOKE_UNIT_PRIC 1.25
 #define BEET_UNIT_PRICE 0.65
 #define CAROTA_UNIT_PRICE 0.89
 #define DISCOUNT 0.05
 #define T_0_5 3.50
 #define T_5_20 10.00
 #define T_20_ 0.1

 int main(){
         double a,b,c,ap,bp,cp,ac,bc,cc,sc,dc,tc;
         ap=ARTICHOKE_UNIT_PRIC;
         bp=BEET_UNIT_PRICE;
         cp=CAROTA_UNIT_PRICE;
         printf("how many artichoke you want(pound):");
         scanf("%lf",&a);
         if(a==)return ;

         printf("how many beet you want(pound):");
         scanf("%lf",&b);
         if(b==)return ;

         printf("how many carota you want(pound):");
         scanf("%lf",&c);
         if(c==)return ;

         printf("\n------UNIT PRICE------\n");
         printf("artichoke's unit price is $%.2f(one pound) \n",ap);
         printf("beet's unit price is $%.2f(one pound)\n",bp);
         printf("carota'unit price is $%.2f(one pound)\n",cp);

         printf("\n------ORDER------\n");
         printf("artichoke:%.2fpound\n",a);
         printf("beet:%.2fpound\n",b);
         printf("carota:%.2fpound\n",c);

         printf("\nartichoke is $%.2f",a*ap);
         printf("\nbeet is $%.2f",b*bp);
         printf("\ncarota is $%.2f\n",c*cp);
         sc=a*ap+b*bp+c*cp;
         printf("\ntotal cost is $%.2f",sc);
         dc=sc>?sc*DISCOUNT:;
         printf("\ndiscount is $%.2f",dc);

         printf("\ntotal weight is %.2f",a+b+c);
         if(<(a+b+c)<=){
                 tc=T_0_5;
         }
         if(<(a+b+c) && (a+b+c)<=){
                 tc=T_5_20;
         }
         if((a+b+c)>){
                 tc=+(a+b+c)*0.1;
         }
         printf("\nttransport cost is $%.2f",tc);
         printf("\norder cost is $%.2f\n",sc-dc+tc);

         return ;
 }

运行结果：

how many artichoke you want(pound):123

how many beet you want(pound):234

how many carota you want(pound):343

------UNIT PRICE------

artichoke's unit price is $1.25(one pound)

beet's unit price is $0.65(one pound)

carota'unit price is $0.89(one pound)

------ORDER------

artichoke:123.00pound

beet:234.00pound

carota:343.00pound

artichoke is $153.75

beet is $152.10

carota is $305.27

total cost is $611.12

discount is $30.56

total weight is 700.00

ttransport cost is $78.00

order cost is $658.56