Segmentation fault around strcpy?

Question

I know that you will rap me over the knuckles but.

Why does it make Segmentation fault

char* cmd;
strcpy(cmd, argv[0]);

when this d

Answer 1

i'm just wondering why this segmentation fault.

Because if cmd is a global variable, its value is NULL, which is not writable, and if it's a local variable, then its value is indeterminate and you should not use it (but it can do anything if you do, which is worse than NULL in many cases).