Question

So, my problem is simple, I whant to create a function to separate the words in the file and parse those words and create an special think for those words, but, I have an error in strcat, when I try to separate the tokens:

look the code:

#include <stdio.h>
#include <string>
#include <Windows.h>

using namespace std;

bool compile(FILE *fp)
{
    char c;
    char token[256];
    bool _return = false;

    while ((c = getc(fp)) != EOF)
    {
        if(isalpha(c))
        {
                    // The error is here
            strcat(token, (char*)c);
            printf("%c\n", c);
        }
        else
        {
            printf("----> %c\n", c);
        }
    }

    printf("%s\n", token);

    return _return;
}

int main()
{
    char *filename = "test.in";

    FILE *fp = fopen(filename, "rb");
    if(!fp)
    {
        return 1;
    }

    if(!compile(fp))
    {
        printf("ERROR...\n");
    }
    fclose(fp);
}

THe code builds normally, but, when I debug, the debugger goes to strcat.asm file 🙁
So, where is my error, thanks for the help. (:

-0-0-0-0-0-0-0-0-0-> edit
And, when I change the strcat to:

strcat(token, &c)

I receive this error from the debugger:

Unhandled exception at 0x20E801F2 in APP.exe: 0xC0000005: Access
violation (parameters: 0x00000008).

Answer 1

strcat expects a null-terminated string; you cannot pass a pointer to an individual character and expect it to work correctly.

Replace

strcat(token, (char*)c);

with

char tmp[2];
tmp[0] = c;
tmp[1] = '\0';
strcat(token, tmp);

to make it work.

You also need to set token[0] to zero to avoid undefined behavior due to it not being initialized.