Read all data from stdin C
c, getchar, posix, stdin, unix
Solution
POSIX-compatible: yes!
You're calling only `getchar()`, `malloc()`, `realloc()` and `free()`, all of which are standard C functions and therefore also available under POSIX. As far as I can tell, you've done all the necessary return code checks too. Given that, the code will be good in any environment that supports `malloc()` and `stdin`.
Problem
I've wrote this small function to read all the data from `stdin`. I need to know if this function is POSIX compatible (by this, I mean it will work under Unix and Unix-like systems) at least it works on Windows... ``` char* getLine() { int i = 0, c; char* ptrBuff = NULL; while ((c = getchar()) != '\n' && c != EOF) { if ((ptrBuff = (char*)realloc(ptrBuff, sizeof (char)+i)) != NULL) ptrBuff[i++] = c; else { free(ptrBuff); return NULL; } } if (ptrBuff != NULL) ptrBuff[i] = '\0'; return ptrBuff; } ``` The function reads all the data from stdin until get `'\n'` or `EOF` and returns a pointer to the new location with all the chars. I don't know if this is the most optimal or safer way to do that, and neither know if this works under Unix and Unix-like systems... so, I need a little bit of help here. How can I improve that function? or is there a better way to get all the data from `stdin` without leaving garbage on the buffer? I know that `fgets()` is an option but, it may leave garbage if the user input is bigger than expected... plus, I want to get all the chars that the user has written. EDIT: New version of `getLine()`: ``` char* readLine() { int i = 0, c; size_t p4kB = 4096; void *nPtr = NULL; char *ptrBuff = (char*)malloc(p4kB); while ((c = getchar()) != '\n' && c != EOF) { if (i == p4kB) { p4kB += 4096; if ((nPtr = realloc(ptrBuff, p4kB)) != NULL) ptrBuff = (char*)nPtr; else { free(ptrBuff); return NULL; } } ptrBuff[i++] = c; } if (ptrBuff != NULL) { ptrBuff[i] = '\0'; ptrBuff = realloc(ptrBuff, strlen(ptrBuff) + 1); } return ptrBuff; } ``` LAST EDIT: This is the final version of the `char* readLine()` function. Now I can't see more bugs neither best ways to improve it, if somebody knows a better way, just tell me, please. ``` char* readLine() { int c; size_t p4kB = 4096, i = 0; void *newPtr = NULL; char *ptrString = malloc(p4kB * sizeof (char)); while (ptrString != NULL && (c = getchar()) != '\n' && c != EOF) { if (i == p4kB * sizeof (char)) { p4kB += 4096; if ((newPtr = realloc(ptrString, p4kB * sizeof (char))) != NULL) ptrString = (char*) newPtr; else { free(ptrString); return NULL; } } ptrString[i++] = c; } if (ptrString != NULL) { ptrString[i] = '\0'; ptrString = realloc(ptrString, strlen(ptrString) + 1); } else return NULL; return ptrString; } ```