programme #include using namespace std; int main() { double r,girth,area; const double PI=3.1415; cout<<"please input radius:\n"; cin>>r; girth=2PIr; area=PIrr; cout<<"radius="<<r<<endl; cout<<"girth="<<girth<<endl; cout<<"area="<<area<<endl; }
#include using namespace std; int main() { int a=451; cout<<a<<endl; cout<<(&a)<<endl; cout<<*(&a)<<endl; }
#include using namespace std; int main() { long int a=10;b=20;t; long int *p1=&a;*p2=&b;,*pt; cout<<p1<<'\t'<<p2<<endl; cout<<*p1<<'\t'<<*p2<<endl; t=*p1;*p1=*p2;*p2=t; cout<<*p1<<'\t'<<*p2<<endl; pt=p1;p1=p2;p2=pt; cout<<p1<<'\t'<<p2<<endl; cout<<*p1<<'\t'<<*p2<<endl; cout<<a<<'\t'<<b<<endl;
}
Void 指针的强制类型转换 #include using namespace std; int main() { int a=65; int ip; void vp=&a; cout<<(int)vp<<endl; cout<<(char)vp<<endl; ip=(int*)vp; cout<<(*ip)<<endl; } 引用测试 #include using namespace std; int main() { int a=2345; int *pa; int &ra=a; pa=&a; cout<<a<<'\t'<<ra<<'\t'<<*pa<<endl; cout<<(&a)<<'\t'<<(&ra)<<'\t'<<pa<<endl; cout<<(&pa)<<endl; } 表达式：算术表达式、逻辑表达式、赋值表达式、条件表达式和逗号表达式 #include using namespace std; int main() { int a; char c; double x; a=2.0/4; x=2.0/4; cout<<a<<'\t'<<x<<endl; a=3+'A'; c=3+'A'; cout<<a<<'\t'<<c<<endl; cout<<3+'A'<<endl; } (a=b)=10 #include using namespace std; int main() { int a,b,c; cin>>a>>b>>c; max=a>b?a>c?a:c:b>c?b:c; cout<<"max="<<max<<endl; }
x=a=3,5*6 x=3
cout<<"Hello!\nWorld.\n"; cout<<"Hello!"<<'\n'<<"World."<<'\n'; cout<<"Hello!"<<endl<<"World."<<endl;
#include #include using namespace std; int main() { int a,b,s; cout.setf(ios::showbase); a=01137;b=023362,s=a+b; cout<<"八进制数"; cout<<oct<<a<<"+"<<b<<"="<<s<<endl; a=239;b=5618;s=a+b; cout<<"十进制数"; cout<<dec<<a<<"+"<<b<<"="<<s<<endl; a=0x1a3e;b=0x4bf;s=a+b; cout<<"十六进制数"; cout<<hex<<a<<"+"<<b<<"="<<s<<endl; } s=0;i=1; loop: if(i<=100) { s+=i; i++; goto loop; }
s=0;i=1; white(i<=100) { s+=i; i++; } s=0;i=1; do {s+=1; i++; } while(i<=100)
for(s=0,i=1;i<=100;i++) { s+=1; i++; }
s=0;i=1; for(;;) { if(i<=100)break; s+=1; i++; }
函数首部和函数体
double max（double x，double y）
{ if（x>y） return x;
else return y;
}
m1=max(a,b)
cout<<max(m1,c)<<endl;
#include
using namespace std;
double max(double,double);
int main()
{ double a,b,c,m1,m2;
cout<<"input a,b,c:\n";
cin>>a>>b>>c;
m1=max(a,b);
m2=max(m1,c);
cout<<"Maximum"<<m2<<endl;
}
double max(double x,double y)
{ if(x>y) return x;
else return y;
}
/求圆柱的体积/
#include
using namespace std;
double volume(double radius,double height);
int main()
{ double vol,r,h;
cout<<"input radius and height:\n";
cin>>r>>h;
vol=volume(r,h);
cout<<"Volume="<<vol<<endl;
}
double volume(double radius,double height)
{ return 3.14radiusradius*height;}
#include
using namespace std;
double max(doubel x,double y,double z);
int main()
{ double a,b,c,s;
cout<<"input a,b,c:\n"<<endl;
cin>>a>>b>>c;
s=max(a,b,c)/(max(a+b,b,c)*max(a,b,b+c));
cout<<"s="<<s<<endl;
}
double max(double x,double y,double z)
{ double m;
if(x>=y) m=x;
else m=y;
if(z>=m) m=z;
return m;
}
#include using namespace std; void swap(int*,int*); int main() { int a=3,b=8; cout<<"before swapping...\n"; cout<<"a="<<a<<",b="<<b<<endl; swap(&a,&b); cout<<"after swapping...\n"; cout<<"a="<<a<<",b="<<b<<endl; } void swap(int *x,int *y) { int temp=*x; *x=*y; *y=temp; }
#include using namespace std; void swap(int&,int&); int main() { int a=3,b=8; cout<<"before swapping...\n"; cout<<"a="<<a<<",b="<<b<<endl; swap(a,b); cout<<"after swapping...\n"; cout<<"a="<<a<<",b="<<b<<endl; } void swap(int &x,int &y) { int temp=x; x=y; y=temp; } #include #include using namespace std; double f(double); double g(double,double); int main() { cout<<"g(2.5,3.4)="<<g(2.5,3.4)<<endl; cout<<"g(1.7,2.5)="<<g(1.7,2.5)<<endl; cout<<"g(3.8,2.9)="<<g(3.8,2.9))<<end; } double g(double x,double y) { if(x,y) return f(x+y)/(f(x)+f(y)); else return f(x-y)/(f(x)+f(y)); } double f(fouble t) { return (1+exp(-t))/(1+exp(-t)); }
#include #include using namespace std; const PI=3.14159; double circlePerimeter(double radius) {return 2PIradius;} double circleArea(double radius) {return PIradiusradius;} double bollArea(double radius) {return 4PIradiusradius;} double bollVolume(double radius) {return 4.0/3PI*pow(radius,3);} int main() { double(*pf)(double); double r,cP,cA,bA,bV; cout<<"enter the radius of a circle:"; cin>>r; pf=circlePerimeter; cP=pf(r); pf=circleArea; cA=pf(r); ...省略 }
统计数字字符个数(包含内联函数) #include #include using namespace std; inline int isnumber(char); int main() { char c; int n; n=0; while((c=getchar())!='\n') if(isnumber(c)) n++; cout<<"n="<<n<<endl;
} int isnumber(char ch) { return (ch>='0'&&ch<='9')?1:0; }