我正试图理解GDB和LLDB，以便我可以在任何时候有效地使用它来调试我的程序。
但我似乎被卡住了：我不知道如何打印像pow，strnlen等C库函数的输出。如果我想探索他们的输出。
以下是LLDB和GDB的输出：

3    int main(int argc,char *argv[]) {
   4       int a = pow(3,2);
-> 5       printf("the value of a is %d",a);
   6       return 0;
   7    }
(lldb) print pow(3,1)
warning: could not load any Objective-C class information. This will significantly reduce the quality of type information available.
error: 'pow' has unknown return type; cast the call to its declared return type
(lldb) print strlen("abc")
warning: could not load any Objective-C class information. This will significantly reduce the quality of type information available.
error: 'strlen' has unknown return type; cast the call to its declared return type
(lldb) expr int a = strlen("abc");
error: 'strlen' has unknown return type; cast the call to its declared return type
(lldb) expr int a = strlen("abc");

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GDB输出：

Starting program: /Users/noobie/workspaces/myWork/pow 
[New Thread 0x1903 of process 35243]
warning: unhandled dyld version (15)

Thread 2 hit Breakpoint 1, main (argc=1, argv=0x7fff5fbffb10) at pow.c:5
5      int a = pow(3,2);
(gdb) print pow(3,2)
No symbol "pow" in current context.
(gdb) set pow(3,2)
No symbol "pow" in current context.
(gdb) set pow(3,2);
No symbol "pow" in current context.
(gdb) print pow(3,2);
No symbol "pow" in current context.
(gdb) call pow(3,2)
No symbol "pow" in current context.
(gdb)

型
我已经编译了程序使用
gcc -g3 pow. c-o pow