第四章 选择结构程序设计习题解答..ppt

第四章 选择结构程序设计习题解答 选择结构程序设计 根据某个变量或表达式的值作出选择，决定执行哪些语句而不执行哪些语句。这样的程序结构称为选择结构或分支结构。 实现选择结构的语句有： 分支语句(if语句)和 多分支语句(switch语句) if-else 择条件语句 if多分支选择语句 if (表达式1)  语句1;else if (表达式2) 语句2;else if (表达式3) 语句3;…………else 语句4;语句5; 开关语句--switch 7、解 #include stdio.h void main() { char c1,c2; scanf(%c%c,c1,c2); if((c1-c2)%2==0) printf(%c,%c,c1+1,c2+1); else printf(%c,%c,c1-1,c2-1); } 8、解 #include stdio.h void main() { int a, b; scanf(%d%d,a,b); if(a%b==0) printf(a/b=%d\n,a/b); else printf(a/b=%d,%d\n,a/b,a%b); } 9、解： #include stdio.h void main() { float x, y; scanf(%f%f,x,y); if((x-2)*(x-2)+(y-2)*(y-2)1) printf(点A在圆外\n); else if((x-2)*(x-2)+(y-2)*(y-2)==1) printf(点A在圆上\n); else printf(点A在圆内\n); } 10 解： #include stdio.h void main() { int year, month,leap; scanf(%d%d,year,month); /*判断是否为闰年*/ if(year%400==0||(year%100!=0year%4==0)) leap=1; else leap=0; switch(month) { case 1: printf(This month has 31 days\n); break; case 2: { if(leap==1) printf(This month has 29 days\n); else printf(This month has 28 days\n); break; } case 3: printf(This month has 31 days\n);break; case 4: printf(This month has 30 days\n);break; case 5: printf(This month has 31 days\n);break; case 6: printf(This month has 30 days\n);break; case 7: printf(This month has 31 days\n);break; case 8: printf(This month has 31 days\n);break; case 9: printf(This month has 30 days\n);break; case 10: printf(This month has 31 days\n);break; case 11: printf(This month has 30 days\n);break; case 12: printf(This month has 31 days\n);break; default: printf(“Month is error data!); } } #include stdio.h void main() { int year, month,leap; scanf(%d%d,year,month); /*判断是否为闰年*/ if(year%400==0||(year%100!=0year%4==0)) leap=1; else leap=0; switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: printf(This month has 31 days\n);break; case