gcc版本
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
/*.int数据类型int类型数据所占内存空间为32位。 其中有符号整型变量取值范围为-2147483648～2147483647， 无符号型整型变量取值范围为0～4294967295U. */
int ia = 2147483647;//int 最大值不越界 int iaOver = 2147483647+1;//越界 //32 64位编译结果一样 cout <<"ia不越界:"<<ia<<endl;//ia不越界:2147483647 cout <<"iaOver越界:"<<iaOver<<endl;//iaOver越界:-2147483648 //32 位编译unsigned int unsigned int uia = 4294967295; unsigned int uiau = 4294967295u; unsigned int uiOver = 4294967295+1; unsigned int uiOveru = 4294967295+1u; cout <<"uia不越界:"<<uia<<endl;//4294967295 cout <<"uiau不越界:"<<uiau<<endl;//4294967295 cout <<"uiOver越界:"<<uiOver<<endl;//0 cout <<"uiOver越界:"<<uiOveru<<endl;//0 */ /*32编译结果 int_long_32_64.cpp:17: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:19: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:20: warning: this decimal constant is unsigned only in ISO C90 */ //64 位编译unsigned int unsigned int uia = 4294967295; unsigned int uiau = 4294967295u; unsigned int uiOver = 4294967295+1; unsigned int uiOveru = 4294967295+1u; cout <<"uia不越界:"<<uia<<endl;//4294967295 cout <<"uiau不越界:"<<uiau<<endl;//4294967295 cout <<"uiOver越界:"<<uiOver<<endl;//0 cout <<"uiOver越界:"<<uiOveru<<endl;//0 //64编译结果 /*int_long_32_64.cpp:34: warning: large integer implicitly truncated to unsigned type int_long_32_64.cpp:35: warning: large integer implicitly truncated to unsigned type */
//long int数据类型 /* 随着宏__WORDSIZE值的改变，long int数据类型的大小也会发生改变。 如果__WORDSIZE的值为32，则long int和int类型一样，占有32位。 在Linux GCC4.0-i386版本中，默认情况下__WORDSIZE的值为32.其定义如下： #include</usr/include/bits/wordsize.h> #define __WORDSIZE 32 在64位机器上，如果__WORDSIZE的值为64， long int类型数据所占内存空间为64位。 其中有长整型变量取值范围为-9223372036854775808L～9223372036854775807L， 无符号长整型变量取值范围为0～18446744073709551615UL.其限制如下： */
//32 位编译long cout<<"查看机器编译器位数:"<<__WORDSIZE<<endl;//32 long la = 2147483647; long laOver = 2147483647+1; long lal = 2147483647l; long laOverl = 2147483647+1l; cout <<"la不越界:"<<la<<endl;//2147483647 cout <<"laOver越界:"<<laOver<<endl;//-2147483648 cout <<"lal不越界:"<<lal<<endl;//0 cout <<"laOverl越界:"<<laOverl<<endl;//-2147483648 //32编译结果 int_long_32_64.cpp: In function ‘int main()’: int_long_32_64.cpp:663: warning: overflow in implicit constant conversion
//64 位编译long cout<<"查看机器编译器位数:"<<__WORDSIZE<<endl;//64 long la = 2147483647; long laOver = 2147483647+1; long lal = 2147483647l; long laOverl = 2147483647+1l; cout <<"la不越界:"<<la<<endl;//2147483647 cout <<"laOver越界:"<<laOver<<endl;//-2147483648 数据末尾未加l(小写L)系统默认为int越界 cout <<"lal不越界:"<<lal<<endl;//0 cout <<"laOverl越界:"<<laOverl<<endl;//2147483648 64位机器此处不越界 //64 位编译结果 int_long_32_64.cpp: In function ‘int main()’: int_long_32_64.cpp:78: warning: overflow in implicit constant conversion
//由于64位的编译器long占8*8位所以将long的最大值进行测试 /* 在64位机器上，如果__WORDSIZE的值为64， long int类型数据所占内存空间为64位。 其中有长整型变量取值范围为-9223372036854775808L～9223372036854775807L， 无符号长整型变量取值范围为0～18446744073709551615UL. */ cout<<"查看机器编译器位数:"<<__WORDSIZE<<endl;//64 long la64 = 9223372036854775807; long laOver64 = 9223372036854775807+1; long lal64 = 9223372036854775807l; long laOverl64 = 9223372036854775807+1l; cout <<"la64不越界:"<<la64<<endl;//9223372036854775807 cout <<"laOver64越界:"<<laOver64<<endl;//-9223372036854775808 cout <<"lal64不越界:"<<lal64<<endl;//9223372036854775807 cout <<"laOverl64越界:"<<laOverl64<<endl;//-9223372036854775808 //64编译 无问题 //32位编译 /*全部越界 int_long_32_64.cpp:97: warning: overflow in implicit constant conversion int_long_32_64.cpp:98: warning: overflow in implicit constant conversion int_long_32_64.cpp:99: warning: overflow in implicit constant conversion int_long_32_64.cpp:100: warning: overflow in implicit constant conversion */
//32 unsinged long /*.int/long数据类型int/long类型数据所占内存空间为32位。 无符号型整型变量取值范围为0～4294967295U. */ unsigned long ul32 = 4294967295; unsigned long ulaOver32 = 4294967295u; unsigned long ulal32 = 4294967295+1; unsigned long ulaOverl32 = 4294967295+1u; cout <<"ul32不越界:"<<ul32<<endl;//4294967295 cout <<"ulaOver32不越界:"<<ulaOver32<<endl;//4294967295 cout <<"ulal32越界:"<<ulal32<<endl;//0 cout <<"ulaOverl32越界:"<<ulaOverl32<<endl;//0 /*32编译结果 int_long_32_64.cpp:122: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:124: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:125: warning: this decimal constant is unsigned only in ISO C90 */
//64 unsinged long //无符号长整型变量取值范围为0～18446744073709551615UL. //其中有长整型变量取值范围为-9223372036854775808L～9223372036854775807L， unsigned long ul64 = 4294967295; unsigned long ulaOver64 = 4294967295u; unsigned long ulal64 = 4294967295+1; unsigned long ulaOverl64 = 4294967295+1u; cout <<"ul64不越界:"<<ul64<<endl;//4294967295 cout <<"ulaOver64不越界:"<<ulaOver64<<endl;//4294967295 cout <<"ulal64不越界:"<<ulal64<<endl;//4294967296 cout <<"ulaOverl64不越界:"<<ulaOverl64<<endl;//4294967296 /*64编译结果 正常无错 */
unsigned long ula64_2 = 18446744073709551615; unsigned long ula64_2u = 18446744073709551615u; unsigned long ula64Over_2 = 18446744073709551615+1; unsigned long ula64Over_2u = 18446744073709551615+1u; cout <<"ula64_2不越界:"<<ula64_2<<endl;//18446744073709551615 cout <<"ula64_2u不越界:"<<ula64_2u<<endl;//18446744073709551615 cout <<"ula64Over_2越界:"<<ula64Over_2<<endl;//0 cout <<"ula64Over_2u越界:"<<ula64Over_2u<<endl;//0 //64编译结果 int_long_32_64.cpp:149:25: warning: integer constant is so large that it is unsigned int_long_32_64.cpp:149: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:151:29: warning: integer constant is so large that it is unsigned int_long_32_64.cpp:151: warning: this decimal constant is unsigned only in ISO C90 int_long_32_64.cpp:152:30: warning: integer constant is so large that it is unsigned int_long_32_64.cpp:152: warning: this decimal constant is unsigned only in ISO C90 */
//32位 long long cout<<"32位编译器 long long占:"<<sizeof(long long)<<endl;//8 //32位的long long 与64位的long 最大数值一样 //取值范围为-9223372036854775808L～9223372036854775807LL， long long lla32 = 9223372036854775807ll;//不加ll错误 过不去 //long long llaOver32 = 9223372036854775807+1ll;//编译错误 过不去 cout <<"lla32不越界:"<<lla32<<endl;//9223372036854775807 //cout <<"llaOver32越界:"<<llaOver32<<endl;//
//64位 long long cout<<"64位编译器 long long占:"<<sizeof(long long)<<endl;//8 //32位的long long 与64位的long 最大数值一样 //取值范围为-9223372036854775808L～9223372036854775807LL， long long lla32 = 9223372036854775807;//9223372036854775807ll long long llaOver32 = 9223372036854775807+1;//9223372036854775807+1ll cout <<"lla32不越界:"<<lla32<<endl;//9223372036854775807 cout <<"llaOver32越界:"<<llaOver32<<endl;//-9223372036854775808 //64位编译结果 //数据结尾加不加ll都一样，可通过
//32位 unsigned long long cout<<"32位编译器 unsigned long long占:"<<sizeof(unsigned long long)<<endl;//8 unsigned long long ulla32 = 18446744073709551615ull;//不加ull错误 过不去 //long long ullaOver32 = 18446744073709551615+1ull;//编译错误 过不去 cout <<"ulla32不越界:"<<ulla32<<endl;//18446744073709551615 //cout <<"ullaOver32越界:"<<ullaOver32<<endl;
//64位 unsigned long long cout<<"64位编译器 unsigned long long占:"<<sizeof(unsigned long long)<<endl;//8 unsigned long long ulla64 = 18446744073709551615;// long long ullaOver64 = 18446744073709551615+1ull;//0 cout <<"ulla64不越界:"<<ulla64<<endl;//18446744073709551615 cout <<"ullaOver64越界:"<<ullaOver64<<endl;
直接gcc test.c不加参数默认为编译器位数，本机为64位；
gcc test.c -m32 按32位编译器编译，反之在64位机上gcc test.c -m64
常用数据类型对应字节数
可用如sizeof（char),sizeof(char*)等得出
32位编译器：
char ：1个字节
char*（即指针变量）: 4个字节（32位的寻址空间是2^32, 即32个bit，也就是4个字节。同理64位编译器）
short int : 2个字节
int： 4个字节
unsigned int : 4个字节
float: 4个字节
double: 8个字节
long: 4个字节
long long: 8个字节
unsigned long: 4个字节
64位编译器：
char ：1个字节
char*(即指针变量): 8个字节
short int : 2个字节
int： 4个字节
unsigned int : 4个字节
float: 4个字节
double: 8个字节
long: 8个字节
long long: 8个字节
unsigned long: 8个字节
参考：http://blog.csdn.net/zhangxinbin5/article/details/7929591 32位和64位系统区别及int字节数
http://paddy-w.iteye.com/blog/1403217 Linux基本数据类型大小——int,char,long int,long long int