C++ remove() and rename() gives "Permission error" - c++

Question

I can't figure out what is happening in my program, it's a simple function to clear all the Windows '\r' from a file, putting all the chars in another file and then rename it to substitute the old file. Every time I execute the function the rename() and remove() functions give me "Permission error" even if I had all the file pointers closed and the file on my PC is closed in every program. Here's the code
static bool correctFile(string fileName) {
string name = fileName;
FILE* test = fopen(fileName.c_str(), "rb");
FILE *in, *out;
char stringTest[1000];
bool isWinFile = false;
if (!test) {
return false;
}
fread(stringTest, 1, 1000, test);
fclose(test);
for (size_t i = 0; i < strlen(stringTest) && !isWinFile; i++) {
if (stringTest[i] == '\r') {
isWinFile = true;
}
}
if (isWinFile) {
in = fopen(fileName.c_str(), "rb");
string tempFile = name + ".temp";
out = fopen(tempFile.c_str(), "wb");
if (!in || !out) {
return false;
}
char temp;
while (fread(&temp, sizeof(temp), 1, in) > 0) {
if (temp != '\r') {
fwrite(&temp, sizeof(temp), 1, out);
}
}
fclose(in);
fclose(out);
if (std::remove(fileName.c_str())) {
std::cerr << "Error: " << strerror(errno);
return false;
}
if (std::rename(tempFile.c_str(), fileName.c_str())) {
return false;
}
}
return true;
}
If you find an error in this please tell me, thanks

Answer 1

I found out that the old file and the new file must not be in the same folder for some reason

Answer 2

Disable the virus scanner and see if the problem persists. Some antivirus products block access to files for a couple of microseconds after they have been written or modified. I know of Kaspersky for example.
I have a "Antivirus" retry loop in some of my batch files because of this. So one (ugly) solution is to retry the rename/remove operations a couple of times.