Introduction to C++ (2)

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This is the 8th day of my participation in Gwen Challenge

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Real,

Scientific enumeration

3e2 =3*10^2
3e-2 = 3*10^2 -
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Single precision

float	4One byte precision type4Bytes (32Bit memory space +/-3.4e +/- 38      (7Bit significant digit)Copy the code

double

double	8Two bytes of double precision accounted for8Bytes (64Bit memory space +/-1.7e +/- 308     (15~16Bit significant digit)Copy the code

Long double

long double	16A one-byte long double16Bytes (128Bit) memory space is available18- 19Bit significant digit.Copy the code

details

// Add f to float,Because the compiler defaults to decimalsdouble, will be compiled fromdoubleintofloat
float a = 3.14 f;

double b= 3.14;

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character

Function:

Display a single characterCopy the code

Grammar:

char ch = 'a'; Byte:1Scope:- 128. 到 127or0 到 255
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Note:

Use single quotation marks to enclose characters, but cannot use double quotation marks. Single quotation marks contain only one character, but cannot contain stringsCopy the code

ASCII and escape characters

// The character variable corresponds to the ASCII encoding 'a'-97 'a' -65
char ch ='a';
cout<<ch<<""< < (int)ch<<endl;

// Commonly used escape characters
\n   // newline ASCII value 10
\t   // Horizontal TAB with ASCII value 9\ \// a backslash

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string

/ / C language
char str[]="hello world";
cout<<str<<endl;

//c++
// start file 
      
string str = "hello world";
cout<<str<<endl;
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Boolean (bool)

// Non-zero is true
// It takes 1 byte
bool flag  = true(nature is1);
cout<<flag<<endl;

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Data input

Standard Input Stream (CIN) The predefined object CIN is an instance of the IoStream class. Cin objects are attached to a standard input device, usually a keyboard. Cin is used in conjunction with the stream extract operator >>,/ / cin > > variables
int a;
cin>>a;
cout<<a;
// Other types are similar

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summary

Also due to acm, I learned c++ in the winter vacation of my freshman year, but it was only simple and basic usage without systematic learning. At that time, I mainly wanted to improve the speed and convenience of code writing, because c++ has STL. But, after all, c + + is an object-oriented language, to say the prior knowledge of c + + is really based on c on the expansion of basically not counting introduction, after learning the Java suddenly to the object-oriented c + + has the interest, with a c + + because of the acm, although object-oriented not to use it, but also have certain obsession on it.