Allocation of buffer in C - c

Question

I am trying to create buffer to store infinity size of symbols.
I have this structure:
typedef struct buffer {
int bufferSize;
int literalSize;
int allocatedSize;
char *bufferPtr;
} bufferStruct;
In my file.h.
I have also functions for buffer:
bufferStruct *BufferInitialize(int size) {
bufferStruct *tempBuff;
tempBuff = (bufferStruct *)malloc(sizeof(bufferStruct));
if (tempBuff == NULL) {
exit(99); // MEMORY_ERROR
}
tempBuff->bufferSize = size;
tempBuff->literalSize = 0;
tempBuff->bufferPtr = NULL;
tempBuff->allocatedSize = 0;
return (tempBuff);
}
int addToBuffer(bufferStruct *buffer, char c) {
if (buffer == NULL) {
return 99; // MEMORY_ERROR
}
if (buffer->allocatedSize > buffer->literalSize) {
buffer->bufferPtr[buffer->literalSize++] = c;
} else {
buffer->bufferPtr = realloc(buffer->bufferPtr, (buffer->allocatedSize + buffer->bufferSize) * sizeof(char));
if (buffer->bufferPtr == NULL) {
return 99; // MEMORY_ERROR
}
buffer->allocatedSize += buffer->bufferSize;
buffer->bufferSize <<= 1; // bS = bS * 2
buffer->bufferPtr[buffer->literalSize++] = c;
}
return 0;
}
int bufferDestroy(bufferStruct *buffer) {
if (buffer == NULL) {
return 99; // MEMORY_ERROR
}
free(buffer->bufferPtr);
free(buffer);
return 0;
}
In my file.c I am trying to create buffer:
token *getNextToken(token *tokenT) {
token *actualToken = NULL;
char *bufferData = NULL;
int charFromFile;
eState state = stateInit;
bufferStruct *bufferT = NULL;
while ((charFromFile = fgetc(fp))) {
switch (state) {
case stateInit: {
if (isdigit(charFromFile)) {
bufferT = BufferInitialize(8);
addToBuffer(bufferT, charFromFile);
state = stateInt;
} else
if (isalpha(charFromFile) || (charFromFile == '_')) {
state = stateId;
bufferT = BufferInitialize(16);
addToBuffer(bufferT, charFromFile);
} else
if (isspace(charFromFile)) {
state = stateInit;
... some more conditions ... it's similar, a lot.
case stateInt: {
if (isdigit(charFromFile)) {
state = stateInt;
addToBuffer(bufferT, charFromFile);
} else
if ((charFromFile == 'e') || (charFromFile == 'E')) {
state = stateExp;
addToBuffer(bufferT, charFromFile);
} else
if (charFromFile = '.') {
state = stateDouble;
addToBuffer(bufferT, charFromFile);
} else {
bufferData = bufferT->bufferPtr;
//strcpy(actualToken->content, bufferData);
addToBuffer(bufferT, '\0');
bufferDestroy(bufferT);
actualToken->type = tokenInt;
return actualToken;
}
} break;
... other similar cases ...
}
}
}
The problem is when I am trying to do this, Visual studio give me error:
One or more multiply defined symbols found
Also gives me
already defined in main.obj
for every function I have.
I don't see the way out. What am I doing wrong ?

Answer 1

There are multiple issues in your code:
You should not put code in header files. The function BufferInitialize should not be located in file.h unless it is defined inline.
The test while (c = fgetc(fp)) is incorrect: you use an assignment as a test expression, it is very error prone, you should at least parenthesize the assignment expression, and probably test for EOF instead of '\0': while ((c = fgetc(fp)) != EOF). Furthermore, c must be defined as an int. Post actual code, not pseudo-code.
You initialize tempBuff->bufferSize to a potentially non zero value, whereas the allocatedSize is 0 and the buffer is unallocated. This seems incorrect.
There could be many more issues in your actual code, we cannot see what the code, how can be tell you about those? Always post a complete, compilable code that demonstrates the problem.