我的代码给出了段错误。 我不知道如何调试，甚至不知道错误在哪里

Question

I just wrote a program to convert infix notation to postfix notation but I'm getting a seg fault. This is the first time I have encountered a segmentation fault and I have no idea how to find where the problem is. I went through the code a few times but I can't find out where my code is trying to access restricted memory space or if there is any other problem causing the seg fault (I'm not even sure what seg fault is).

I'm not sure if I'm allowed to paste the whole code over here. So, I'm putting this up on pastebin : http://pastebin.com/M0mTU8Jg

Another question: In my code at line 13, if I replace strcat(")",infix) with infix[strlen(infix)]=")" , I get this warning: warning: assignment makes integer from pointer without a cast [enabled by default] . What is the cause of this warning? Similar statements later in the program do not raise any warnings for example in line no. 24

EDIT: The seg fault was because I had used wrong order of arguments in the strcat() function so it was trying to append string to a constant that is a read only memory.

Nevermind the second question, I was assigning a string (char *) to a char so the warning. Just needed to replace double quotes with single quotes.

Answer 1

You do really need to know how to use a debugger and find what line your code is segfaulting on, it's an important skill. That being said, I see one cause immediately:

strcat(")",infix);

strcat(char * dest, cosnt char * src) appends to dest , and in this case dest is a string constant stored in read only memory. Maybe all that is necessary is to reverse the order of the arguments to strcat() , but I don't know your intentions with the infix variable.

Answer 2

Can you run your code with debugger? It will show you what line seg fault will happen. Here's about segfault: http://en.wikipedia.org/wiki/Segmentation_fault