linux命令行：传递错误的参数？

Question

I'm debugging my C++ code on Ubuntu which I execute as ./main path < input.txt

argv[1] should contain a string "path" which verified by GDB below.

However, the program always jumps over my first condition even though argv[1] == "path" should return true.

Any idea?

...
(gdb) n
181     if(argv[1] == "path")
(gdb) p argv[1]
$1 = 0xbffffba3 "path"
(gdb) n
183     else if(argc == 1)
(gdb) 

Answer 1

Even though the two strings are the same, they occupy a different location in memory. When it is checking whether argv[1] is equal to a fixed-string "path" , it is not doing it character-by-character: it is looking to see whether the pointer to the fixed-string "path" is the same as the argv[1] variable passed into main() , which it is not.

You need to use strcmp to test the equality of those two strings:

if (strcmp(argv[1], "path") == 0) { /* they match */ }