如何将指针指向的textf的内容复制到char数组（即，指针-> char数组）

Question

I am reading from a file, which, thanks to malloc, saves the content of the text file to *buffer. However, I wish to transfer the contents of file to a char array. How can I accomplish this?

Here is my code so far:

#define LENGTH_OF_INPUT 49

FILE *FP = fopen("InputString.txt", "r");

char *buffer;
char InputString;

fseek(FP, 0L, SEEK_END);
s = ftell(FP);
rewind(FP);
buffer = (char*) malloc(s); /* buffer now is the content of the file */

if (buffer != NULL) /* If buffer was allocated... i.e the file exists*/
    {
    fread(buffer, s, 1, FP);
    fclose(FP); /* Must.. Close.. File.. */

    FP = NULL; /* For decaying pointer?? */

for (sizeofbuffer = 0; *buffer != '\0'; ++sizeofbuffer)
{
    *buffer++;
}

if (sizeofbuffer == LENGTH_OF_INPUT - 1 ) /* Check if the length of the string = 48 */
    {
        /* Correct length! */

        /* Also need to reset *buffer so that this for loop copies from the first letter */

        for (i = 0; *buffer != '\0' ; ++sizeofbuffer) /* Save to InputString*/
        {
            /* CODE NEEDS TO GO HERE!! */
        }
    }

I don't want to use strcpy in case the char array contains an early '\\0'

EDIT: I found this http://www.cplusplus.com/forum/general/4107/ ; don't understand it though (is it even relevant?)

Answer 1

Change this:

buffer = (char*)malloc(s);

To this:

buffer = (char*)malloc(s+1);
buffer[s] = 0;

And return buffer after you close the file; the rest of the code is redundant. In addition to that, don't forget to free the memory pointed by buffer at some later point in the execution of your program.

---

The purpose of buffer[s] = 0 is for you to be able to pass it to string functions. A few examples:

printf("%s",buffer);
strcpy(buffer2,buffer);
strcat(buffer2,buffer);
if (strcmp(buffer2,buffer) == 0) ...

Even if you're not interested in that, you still need a method with which you can detect the end of the string which is stored in the memory pointed by buffer . The answer above suggests the method of setting buffer[s] to a 0 (null) character. Alternatively, you can simply use the value of s itself. However, if you choose this method, then you'll have to maintain both buffer and s in a structure.