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C++结构体内存对齐跨平台测试
测试1，不规则对齐数据。
Code:
#include <stdio.h>#pragma pack(push)#pragma pack(8)struct Test8{ char a; long long b; char d;};#pragma pack(pop)#pragma pack(push)#pragma pack(4)struct Test4{ char a; long long b; char d;};#pragma pack(pop)#pragma pack(push)#pragma pack(1)struct Test1{ char a; long long b; char d;};#pragma pack(pop)struct Test0{ char a; long long b; char d;};int main(){ printf("sizeof(void*)=%d\n", sizeof(void*)); printf("sizeof(long long)=%d\n", sizeof(long long)); printf("sizeof(Test8)=%d\n", sizeof(struct Test8)); printf("sizeof(Tes4)=%d\n", sizeof(struct Test4)); printf( "sizeof(Test1)=%d\n", sizeof(struct Test1)); printf("sizeof(Test0)=%d\n", sizeof(struct Test0)); return 0;}
Output msvc x86:
sizeof(void*)=4sizeof(long long)=8sizeof(Test8)=24sizeof(Tes4)=16sizeof(Test1)=10sizeof(Test0)=24
Output msvc x64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test8)=24sizeof(Tes4)=16sizeof(Test1)=10sizeof(Test0)=24
Output xcode IOS armV7:
sizeof(void*)=4sizeof(long long)=8sizeof(Test8)=16sizeof(Tes4)=16sizeof(Test1)=10sizeof(Test0)=16
Output xcode IOS arm64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test8)=24sizeof(Tes4)=16sizeof(Test1)=10sizeof(Test0)=24
Android armv7 simulator output code:
__android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(void*)=%d\n", sizeof(void*)); __android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(long long)=%d\n", sizeof(long long)); __android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(Test8)=%d\n", sizeof(Test8)); __android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(Tes4)=%d\n", sizeof(Test4)); __android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(Test1)=%d\n", sizeof(Test1)); __android_log_print(ANDROID_LOG_DEBUG, "JNITag", "sizeof(Test0)=%d\n", sizeof(Test0));
Android armv7 simulator Output:
D/JNITag: sizeof(void*)=4D/JNITag: sizeof(long long)=8D/JNITag: sizeof(Test8)=16D/JNITag: sizeof(Tes4)=16D/JNITag: sizeof(Test1)=10D/JNITag: sizeof(Test0)=16
测试二，简单数组测试，源码：
#include <stdio.h>#pragma pack(push)#pragma pack(8)struct Test8{ char a[3];};#pragma pack(pop)#pragma pack(push)#pragma pack(4)struct Test4{ char a[3];};#pragma pack(pop)#pragma pack(push)#pragma pack(1)struct Test1{ char a[3];};#pragma pack(pop)struct Test0{ char a[3];};int main(){ printf("sizeof(void*)=%d\n", sizeof(void*)); printf("sizeof(long long)=%d\n", sizeof(long long)); printf("sizeof(Test8)=%d\n", sizeof(struct Test8)); printf("sizeof(Tes4)=%d\n", sizeof(struct Test4)); printf( "sizeof(Test1)=%d\n", sizeof(struct Test1)); printf("sizeof(Test0)=%d\n", sizeof(struct Test0)); return 0;}
msvc x86:
sizeof(void*)=4sizeof(long long)=8sizeof(Test8)=3sizeof(Tes4)=3sizeof(Test1)=3sizeof(Test0)=3
msvc x64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test8)=3sizeof(Tes4)=3sizeof(Test1)=3sizeof(Test1)=3
iphone armv7:
sizeof(void*)=4sizeof(long long)=8sizeof(Test8)=3sizeof(Tes4)=3sizeof(Test1)=3sizeof(Test0)=3
iphone arm64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test8)=3sizeof(Tes4)=3sizeof(Test1)=3sizeof(Test0)=3
android armv7 simulator:
D/JNITag: sizeof(void*)=4D/JNITag: sizeof(long long)=8D/JNITag: sizeof(Test8)=3D/JNITag: sizeof(Tes4)=3D/JNITag: sizeof(Test1)=3D/JNITag: sizeof(Test0)=3
测试三，当结构体包含pack1的结构体时
code：
#include <stdio.h>#include <stddef.h>#pragma pack(push)#pragma pack(1)struct Test1{ char a[3]; long long b; char d[2]; int e;};#pragma pack(pop)#pragma pack(push)#pragma pack(8)struct Owner8{ char c1; struct Test1 a; int i2;};#pragma pack(pop)#pragma pack(push)#pragma pack(4)struct Owner4{ char c1; struct Test1 a; int i2;};#pragma pack(pop)#pragma pack(push)#pragma pack(1)struct Owner1{ char c1; struct Test1 a; int i2;};#pragma pack(pop)struct Owner0{ char c1; struct Test1 a; int i2;};int main(){ printf("sizeof(void*)=%d\n", sizeof(void*)); printf("sizeof(long long)=%d\n", sizeof(long long)); printf( "sizeof(Test1)=%d\n", sizeof(struct Test1)); printf("---------------------------------------\n"); printf("sizeof(Owner8)=%d\n", sizeof(struct Owner8)); printf("offsetof(Owner8, a)=%d\n", offsetof( struct Owner8, a)); printf("offsetof(Owner8, i2)=%d\n", offsetof( struct Owner8, i2)); printf("---------------------------------------\n"); printf("sizeof(Owner4)=%d\n", sizeof(struct Owner4)); printf("offsetof(Owner4, a)=%d\n", offsetof( struct Owner4, a)); printf("offsetof(Owner4, i2)=%d\n", offsetof( struct Owner4, i2)); printf("---------------------------------------\n"); printf("sizeof(Owner1)=%d\n", sizeof(struct Owner1)); printf("offsetof(Owner1, a)=%d\n", offsetof( struct Owner1, a)); printf("offsetof(Owner1, i2)=%d\n", offsetof( struct Owner1, i2)); printf("---------------------------------------\n"); printf("sizeof(Owner0)=%d\n", sizeof(struct Owner0)); printf("offsetof(Owner0, a)=%d\n", offsetof( struct Owner0, a)); printf("offsetof(Owner0, i2)=%d\n", offsetof( struct Owner0, i2)); return 0;}
msvc x86:
sizeof(void*)=4sizeof(long long)=8sizeof(Test1)=17---------------------------------------sizeof(Owner8)=24offsetof(Owner8, a)=1offsetof(Owner8, i2)=20---------------------------------------sizeof(Owner4)=24offsetof(Owner4, a)=1offsetof(Owner4, i2)=20---------------------------------------sizeof(Owner1)=22offsetof(Owner1, a)=1offsetof(Owner1, i2)=18---------------------------------------sizeof(Owner0)=24offsetof(Owner0, a)=1offsetof(Owner0, i2)=20
msvc x64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test1)=17---------------------------------------sizeof(Owner8)=24offsetof(Owner8, a)=1offsetof(Owner8, i2)=20---------------------------------------sizeof(Owner4)=24offsetof(Owner4, a)=1offsetof(Owner4, i2)=20---------------------------------------sizeof(Owner1)=22offsetof(Owner1, a)=1offsetof(Owner1, i2)=18---------------------------------------sizeof(Owner0)=24offsetof(Owner0, a)=1offsetof(Owner0, i2)=20
xcode ios armv7:
sizeof(void*)=4sizeof(long long)=8sizeof(Test1)=17---------------------------------------sizeof(Owner8)=24offsetof(Owner8, a)=1offsetof(Owner8, i2)=20---------------------------------------sizeof(Owner4)=24offsetof(Owner4, a)=1offsetof(Owner4, i2)=20---------------------------------------sizeof(Owner1)=22offsetof(Owner1, a)=1offsetof(Owner1, i2)=18---------------------------------------sizeof(Owner0)=24offsetof(Owner0, a)=1offsetof(Owner0, i2)=20
xcode ios arm64:
sizeof(void*)=8sizeof(long long)=8sizeof(Test1)=17---------------------------------------sizeof(Owner8)=24offsetof(Owner8, a)=1offsetof(Owner8, i2)=20---------------------------------------sizeof(Owner4)=24offsetof(Owner4, a)=1offsetof(Owner4, i2)=20---------------------------------------sizeof(Owner1)=22offsetof(Owner1, a)=1offsetof(Owner1, i2)=18---------------------------------------sizeof(Owner0)=24offsetof(Owner0, a)=1offsetof(Owner0, i2)=20
android armv7 simulator:
D/JNITag: sizeof(void*)=4D/JNITag: sizeof(long long)=8D/JNITag: sizeof(Test1)=17D/JNITag: ---------------------------------------D/JNITag: sizeof(Owner8)=24D/JNITag: offsetof(Owner8, a)=1D/JNITag: offsetof(Owner8, i2)=20D/JNITag: ---------------------------------------D/JNITag: sizeof(Owner4)=24D/JNITag: offsetof(Owner4, a)=1D/JNITag: offsetof(Owner4, i2)=20D/JNITag: ---------------------------------------D/JNITag: sizeof(Owner1)=22D/JNITag: offsetof(Owner1, a)=1D/JNITag: offsetof(Owner1, i2)=18D/JNITag: ---------------------------------------D/JNITag: sizeof(Owner0)=24D/JNITag: offsetof(Owner0, a)=1D/JNITag: offsetof(Owner0, i2)=20
C++结构体内存对齐跨平台测试
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