【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）：
1 #include <stdio.h> 2 3 int main(){ 4 int space=0,newline=0,other=0; 5 char ch; 6 printf("please enter something:\n"); 7 while((ch=getchar())!='#'){ 8 if(ch=='\n'){ 9 newline+=1; 10 }else if(ch==' '){ 11 space+=1; 12 }else{ 13 other+=1; 14 } 15 } 16 printf("space is %d\n",space); 17 printf("newline is %d\n",newline); 18 printf("other is %d\n",other); 19 return 0; 20 }
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）：
1 #include <stdio.h> 2 #define ARTICHOKE_UNIT_PRIC 1.25 3 #define BEET_UNIT_PRICE 0.65 4 #define CAROTA_UNIT_PRICE 0.89 5 #define DISCOUNT 0.05 6 #define T_0_5 3.50 7 #define T_5_20 10.00 8 #define T_20_ 0.1 9 10 int main(){ 11 double a,b,c,ap,bp,cp,ac,bc,cc,sc,dc,tc; 12 ap=ARTICHOKE_UNIT_PRIC; 13 bp=BEET_UNIT_PRICE; 14 cp=CAROTA_UNIT_PRICE; 15 printf("how many artichoke you want(pound):"); 16 scanf("%lf",&a); 17 if(a==0)return 0; 18 19 printf("how many beet you want(pound):"); 20 scanf("%lf",&b); 21 if(b==0)return 0; 22 23 printf("how many carota you want(pound):"); 24 scanf("%lf",&c); 25 if(c==0)return 0; 26 27 printf("\n------UNIT PRICE------\n"); 28 printf("artichoke's unit price is $%.2f(one pound) \n",ap); 29 printf("beet's unit price is $%.2f(one pound)\n",bp); 30 printf("carota'unit price is $%.2f(one pound)\n",cp); 31 32 printf("\n------ORDER------\n"); 33 printf("artichoke:%.2fpound\n",a); 34 printf("beet:%.2fpound\n",b); 35 printf("carota:%.2fpound\n",c); 36 37 printf("\nartichoke is $%.2f",a*ap); 38 printf("\nbeet is $%.2f",b*bp); 39 printf("\ncarota is $%.2f\n",c*cp); 40 sc=a*ap+b*bp+c*cp; 41 printf("\ntotal cost is $%.2f",sc); 42 dc=sc>100?sc*DISCOUNT:0; 43 printf("\ndiscount is $%.2f",dc); 44 45 printf("\ntotal weight is %.2f",a+b+c); 46 if(0<(a+b+c)<=5){ 47 tc=T_0_5; 48 } 49 if(5<(a+b+c) && (a+b+c)<=20){ 50 tc=T_5_20; 51 } 52 if((a+b+c)>20){ 53 tc=8+(a+b+c)*0.1; 54 } 55 printf("\nttransport cost is $%.2f",tc); 56 printf("\norder cost is $%.2f\n",sc-dc+tc); 57 58 return 0; 59 }
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
