C、C++資料型別(int, long, short, char, long long) 的取值範圍、最大最小值：climits 裡的一些巨集
阿新 • • 發佈：2019-02-16
#include <iostream> #include <climits> using namespace std; int main() { cout << "int is " <<sizeof(int) << " bytes." << endl; cout << "short is " <<sizeof(short) << " bytes." << endl; cout << "long is " <<sizeof(long) << " bytes." << endl; cout << "long long is " <<sizeof(long long) << " bytes." << endl; cout << endl; cout << "*****Maximum values:*****" << endl; cout << "int: " << INT_MAX << endl; cout << "short: " << SHRT_MAX << endl; cout << "long: " << LONG_MAX << endl; cout << "long long: " << LLONG_MAX << endl; cout << "long long: " << LONG_LONG_MAX << endl;//和上一個相同 cout << "char: " << CHAR_MAX << endl; cout << "signed char: " << SCHAR_MAX << endl; cout << "unsigned char: " << CHAR_MAX << endl; cout << "unsigned short: " << USHRT_MAX << endl; // cout << "unsigned int: " << UNIT_MAX << endl;//報錯 cout << "unsigned long: " << ULONG_MAX << endl; cout << "unsigned long long: " << ULLONG_MAX << endl; cout << "unsigned long long: " << ULONG_LONG_MAX << endl;//和上一個相同 cout << endl; cout << "*****Minimum values:*****" << endl; cout << "int: " << INT_MIN << endl; cout << "short: " << SHRT_MIN << endl; cout << "long: " << LONG_MIN << endl; cout << "long long: " << LLONG_MIN << endl; cout << "long long: " << LONG_LONG_MIN << endl;//和上一個相同 cout << "char: " << CHAR_MIN << endl; cout << "signed char: " << SCHAR_MIN << endl; cout << endl; cout<<"Bits per byte = "<<CHAR_BIT<<endl; return 0; }
64位win7執行結果 int is 4 bytes. short is 2 bytes. long is 4 bytes. long long is 8 bytes. *****Maximum values:***** int: 2147483647 short: 32767 long: 2147483647 long long: 9223372036854775807 long long: 9223372036854775807 char: 127 signed char: 127 unsigned char: 127 unsigned short: 65535 unsigned long: 4294967295 unsigned long long: 18446744073709551615 unsigned long long: 18446744073709551615 *****Minimum values:***** int: -2147483648 short: -32768 long: -2147483648 long long: -9223372036854775808 long long: -9223372036854775808 char: -128 signed char: -128 Bits per byte = 8
#include<iostream> #include<string> #include <limits> using namespace std; int main() { cout << "type: \t\t" << "************size**************"<< endl; cout << "bool: \t\t" << "所佔位元組數：" << sizeof(bool); cout << "\t最大值：" << (numeric_limits<bool>::max)(); cout << "\t\t最小值：" << (numeric_limits<bool>::min)() << endl; cout << "char: \t\t" << "所佔位元組數：" << sizeof(char); cout << "\t最大值：" << (numeric_limits<char>::max)(); cout << "\t\t最小值：" << (numeric_limits<char>::min)() << endl; cout << "signed char: \t" << "所佔位元組數：" << sizeof(signed char); cout << "\t最大值：" << (numeric_limits<signed char>::max)(); cout << "\t\t最小值：" << (numeric_limits<signed char>::min)() << endl; cout << "unsigned char: \t" << "所佔位元組數：" << sizeof(unsigned char); cout << "\t最大值：" << (numeric_limits<unsigned char>::max)(); cout << "\t\t最小值：" << (numeric_limits<unsigned char>::min)() << endl; cout << "wchar_t: \t" << "所佔位元組數：" << sizeof(wchar_t); cout << "\t最大值：" << (numeric_limits<wchar_t>::max)(); cout << "\t\t最小值：" << (numeric_limits<wchar_t>::min)() << endl; cout << "short: \t\t" << "所佔位元組數：" << sizeof(short); cout << "\t最大值：" << (numeric_limits<short>::max)(); cout << "\t\t最小值：" << (numeric_limits<short>::min)() << endl; cout << "int: \t\t" << "所佔位元組數：" << sizeof(int); cout << "\t最大值：" << (numeric_limits<int>::max)(); cout << "\t最小值：" << (numeric_limits<int>::min)() << endl; cout << "unsigned: \t" << "所佔位元組數：" << sizeof(unsigned); cout << "\t最大值：" << (numeric_limits<unsigned>::max)(); cout << "\t最小值：" << (numeric_limits<unsigned>::min)() << endl; cout << "long: \t\t" << "所佔位元組數：" << sizeof(long); cout << "\t最大值：" << (numeric_limits<long>::max)(); cout << "\t最小值：" << (numeric_limits<long>::min)() << endl; cout << "unsigned long: \t" << "所佔位元組數：" << sizeof(unsigned long); cout << "\t最大值：" << (numeric_limits<unsigned long>::max)(); cout << "\t最小值：" << (numeric_limits<unsigned long>::min)() << endl; cout << "double: \t" << "所佔位元組數：" << sizeof(double); cout << "\t最大值：" << (numeric_limits<double>::max)(); cout << "\t最小值：" << (numeric_limits<double>::min)() << endl; cout << "long double: \t" << "所佔位元組數：" << sizeof(long double); cout << "\t最大值：" << (numeric_limits<long double>::max)(); cout << "\t最小值：" << (numeric_limits<long double>::min)() << endl; cout << "float: \t\t" << "所佔位元組數：" << sizeof(float); cout << "\t最大值：" << (numeric_limits<float>::max)(); cout << "\t最小值：" << (numeric_limits<float>::min)() << endl; cout << "size_t: \t" << "所佔位元組數：" << sizeof(size_t); cout << "\t最大值：" << (numeric_limits<size_t>::max)(); cout << "\t最小值：" << (numeric_limits<size_t>::min)() << endl; cout << "string: \t" << "所佔位元組數：" << sizeof(string) << endl; // << "\t最大值：" << (numeric_limits<string>::max)() << "\t最小值：" << (numeric_limits<string>::min)() << endl; cout << "type: \t\t" << "************size**************"<< endl; return 0; }
64位win7執行結果
type: *****************************SIZE****************************
bool: 所佔位元組數：1 最大值：1 最小值：0
char: 所佔位元組數：1 最大值： 最小值：€
signed char: 所佔位元組數：1 最大值： 最小值：€
unsigned char: 所佔位元組數：1 最大值： 最小值：
wchar_t: 所佔位元組數：2 最大值：65535 最小值：0
short: 所佔位元組數：2 最大值：32767 最小值：-32768
int: 所佔位元組數：4 最大值：2147483647 最小值：-2147483648
unsigned: 所佔位元組數：4 最大值：4294967295 最小值：0
long: 所佔位元組數：4 最大值：2147483647 最小值：-2147483648
unsigned long: 所佔位元組數：4 最大值：4294967295 最小值：0
double: 所佔位元組數：8 最大值：1.79769e+308 最小值：2.22507e-308
long double: 所佔位元組數：12 最大值：Infinity 最小值：0
float: 所佔位元組數：4 最大值：3.40282e+38 最小值：1.17549e-38
size_t: 所佔位元組數：4 最大值：4294967295 最小值：0
string: 所佔位元組數：4
type: *****************************SIZE****************************/*執行結果分析：
以上結果已經很明白了，一下補充說明幾點：
概念、整型：表示整數、字元和布林值的算術型別合稱為整型（integral type）。
關於帶符號與無符號型別：整型 int、stort 和 long 都預設為帶符號型。要獲得無符號型則必須制定該型別為unsigned，比如unsigned long。unsigned int型別可以簡寫為unsigned，也就是說，unsigned後不加其他型別說明符就意味著是unsigned int。
一位元組表示八位，即：1byte = 8 bit;
int: 4byte = 32 bit有符號signed範圍：2^31-1 ~ -2^31即：2147483647 ~ -2147483648無符號unsigned範圍：2^32-1 ~ 0即：4294967295 ~ 0
long: 4 byte = 32 bit同int型
double: 8 byte = 64 bit範圍：1.79769e+308 ~ 2.22507e-308
long double: 12 byte = 96 bit範圍： 1.18973e+4932 ~ 3.3621e-4932
float: 4 byte = 32 bit範圍： 3.40282e+038 ~ 1.17549e-038
int、unsigned、long、unsigned long 、double的數量級最大都只能表示為10億，即它們表示十進位制的位數不超過10個，即可以儲存所有9位整數。而short只是能表示5位；
另外對於浮點說而言：使用double型別基本上不會有錯。在float型別中隱式的精度損失是不能忽視的，二雙精度計算的代價相對於單精度可以忽略。事實上，在有些機器上，double型別比float型別的計算要快得多。float型只能保證6位有效數字，而double型至少可以保證15位有效數字（小數點後的數位），long double型提供的精度通常沒有必要，而且還要承擔額外的執行代價。
double是8位元組共64位，其中小數位佔52位，2-^52=2.2204460492503130808472633361816e-16，量級為10^-16，故能夠保證2^-15的所有精度。
在有些機器上，用long型別進行計算所付出的執行時代價遠遠高於用int型別進行同樣計算的代價，所以算則型別前要先了解程式的細節並且比較long型別與int型別的實際執行時效能代價。