这合法吗？

Sun编译器提供 " b.c"，第6行：警告：未命名的工会成员 " b.c"，第10行：警告：未命名的工会成员 " b.c"，第11行：零大小的struct / union cc：acomp因bc而失败 gcc -Wall -ansi -pedantic bc给出 bc：在函数`main''： bc：6：警告：ANSI C禁止成员声明没有成员 bc：6：警告：未命名的struct / union定义没有实例 bc：10：警告：ANSI C禁止没有成员的成员声明 bc：10：警告：未命名的struct / union，它不定义实例 bc：11：警告：工会没有会员 bc：11：警告：未使用的变量`un'' bc：12：警告：控制到达无效功能的结束 我建议你把你的编译器警告 升级。如果您仍然没有收到警告，那么转换到新编译器的时间是 。 Annonymous Union的主要用途是限制某些名称的范围 空间。如果你要定义Anno。工会，你必须自己照顾 变量的范围。 Hi all,I wanted to have a union which has two structures in it.So i did this,union {struct{int a;int b;};struct{float c;};}un;I did not want to name the two inner structures, because i wanted toaccess the members like this,<union name>.<member name>instead of<union name>.<structure name>.<member name>My question is, Is this valid C?I also observed that if i have a union like this ,union {struct{int a;int b;};struct{float a;float b;};}un;Compiler doesn''t give me any error.If i say, ''un.a'' how will it know whether i''m using float a or inta ?Thanks for your time,Yugi. 解决方案No. The compiler cannot read your mind and realizethat when you write <union name>.<member name>you really mean <union name>.<some structure>.<member name>It won''t. Hence your definition is useless even if itdoesn''t cause your compiler to complain. For theprogrammeint main(void) {union {struct{int a;int b;};struct{float a;float b;};}un;}Sun compiler gives"b.c", line 6: warning: unnamed union member"b.c", line 10: warning: unnamed union member"b.c", line 11: zero-sized struct/unioncc: acomp failed for b.cgcc -Wall -ansi -pedantic b.c givesb.c: In function `main'':b.c:6: warning: ANSI C forbids member declarations with no membersb.c:6: warning: unnamed struct/union that defines no instancesb.c:10: warning: ANSI C forbids member declarations with no membersb.c:10: warning: unnamed struct/union that defines no instancesb.c:11: warning: union has no membersb.c:11: warning: unused variable `un''b.c:12: warning: control reaches end of non-void functionI would suggest that you turn your compiler''s warninglevels up. If you still don''t get a warning then it''s timeto switch to a new compiler.No. The compiler cannot read your mind and realizethat when you write <union name>.<member name>you really mean <union name>.<some structure>.<member name>It won''t. Hence your definition is useless even if itdoesn''t cause your compiler to complain. For theprogrammeint main(void) { union { struct{ int a; int b; }; struct{ float a; float b; }; }un;}Sun compiler gives"b.c", line 6: warning: unnamed union member"b.c", line 10: warning: unnamed union member"b.c", line 11: zero-sized struct/unioncc: acomp failed for b.cgcc -Wall -ansi -pedantic b.c givesb.c: In function `main'':b.c:6: warning: ANSI C forbids member declarations with no membersb.c:6: warning: unnamed struct/union that defines no instancesb.c:10: warning: ANSI C forbids member declarations with no membersb.c:10: warning: unnamed struct/union that defines no instancesb.c:11: warning: union has no membersb.c:11: warning: unused variable `un''b.c:12: warning: control reaches end of non-void functionI would suggest that you turn your compiler''s warninglevels up. If you still don''t get a warning then it''s timeto switch to a new compiler.The main usage of Annonymous Union is to limit scope of some namespace. If you are defining Anno. union, you have to take care scope ofvariable yourself. 这篇关于这合法吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！