三元运算符c ++中的return语句

I wrote the absolute function using ternary operator as follows

int abs(int a) {
 a >=0 ? return a : return -a;
}

我收到以下错误消息

../src/templates.cpp: In function ‘int abs(int)’:
../src/templates.cpp:4: error: expected primary-expression before ‘return’
../src/templates.cpp:4: error: expected ‘:’ before ‘return’
../src/templates.cpp:4: error: expected primary-expression before ‘return’
../src/templates.cpp:4: error: expected ‘;’ before ‘return’
../src/templates.cpp:4: error: expected primary-expression before ‘:’ token
../src/templates.cpp:4: error: expected ‘;’ before ‘:’ token
../src/templates.cpp:5: warning: no return statement in function returning non-void

如果我这样写

return a>=0 ? a : -a;

我没有收到任何错误.两者有什么区别?

 return a