Я работаю над школьным проектом, в котором мне нужно хранить данные PPM в структурах.У меня есть проблема с массивом строк внутри структуры.
typedef struct {
char **comments;
} PPM;
У меня есть 3 функции, которые используют эту структуру.
PPM * getPPM () используется для получения всех данных PPM из файла и сохранения их в структуре
void showPPM (PPM * img) для отображения данных изображенияв клемме
PPM * кодировать (PPM * img) , который используется для изменения младшего разряда значений RGB изображения
Проблема в том, что getPPM работает как задумано и получает все комментарии в массив комментариев в getPPM.Они отображаются нормально, если я делаю это так:
PPM *p = getPPM(fin);
showPPM(p);
Но если я пытаюсь вызвать его с помощью функции кодирования, например:
PPM *p = getPPM(fin);
PPM *g = encode(p);
showPPM(g);
, отладчик показывает, что как толькопрограмма входит в функцию encode , значение комментариев сбрасывается в NULL, даже если эта функция даже не касается комментариев.Я неправильно называю эти функции или что-то не так с моим кодом?Я постараюсь предоставить минимальный код, если проблема не в способе вызова функций, так как код большой и все зависит друг от друга.
Я очень плохо знаком с языком Си.Я пытался понять проблему часами, но нигде не смог найти решения.Любая помощь будет принята с благодарностью.
РЕДАКТИРОВАТЬ: Это так мало, как я мог бы сделать.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//Structures
typedef struct {
int r, g, b;
} pixels;
typedef struct {
char format[3];
char **comments;
int width, height, maxColors, commentCounter;
pixels **pixelValues;
} PPM;
// Functions declarations
PPM *getPPM(FILE * f);
PPM *encode(PPM *im, char *message, unsigned int mSize, unsigned int secret);
void showPPM(PPM * im);
static int *decimalToBinary(const char *message, unsigned int length);
// Main method
int main(int argc, char **argv) {
FILE * fin = fopen(argv[1], "r");
if(fin == NULL) {
perror("Cannot open file");
exit(1);
}
PPM *p = getPPM(fin);
PPM *g = encode(p, "test", 5, 1);
showPPM(g);
return 0;
}
/*
* This function is used to get the image data from a file and populate
* our strutures with it.
*/
PPM *getPPM(FILE * f) {
// Allocate the memory for structure and check if it was successful
PPM *pic = (PPM *) malloc(sizeof(PPM));
if(!pic) {
perror("Unable to allocate memory for structure");
exit(1);
}
char line[100]; // Expecting no more than 100 characters per line.
pic->commentCounter = 0; // This is the counter to keep size if there are more than one comments
int pixelsCounter = 0; // Counter for pixels' array
pic->comments = malloc(sizeof(char *));
pic->pixelValues = malloc(sizeof(PPM));
int lineCounter = 0;
if((pic->comments) == NULL) {
perror("Unable to allocate memory for pixels");
exit(1);
}
while(fgets(line, sizeof(line), f)) {
// Reference: /2254143/udalenie-zavershayschego-simvola-novoi-stroki-iz-vvoda-fgets
size_t length = strlen(line);
if(length > 0 && line[length-1] == '\n') {
line[--length] = '\0';
}
// Assigning the file format
if(line[0] == 'P') {
pic->format[0] = line[0];
pic->format[1] = line[1];
pic->format[2] = '\0';
}
//Populate comments into struct PPM
if(line[0] == '#') {
// Reallocate/allocate the array size each time a new line of comment is found
if(pic->commentCounter != 0) {
pic->comments = realloc(pic->comments, (pic->commentCounter+1) * sizeof(char *));
}
// Allocate the memory for the string
pic->comments[pic->commentCounter] = malloc(100 * sizeof(char));
// Write the at commentCounter position of the array; character by character
int i = 0;
while(line[i] != '\0') {
pic->comments[pic->commentCounter][i] = line[i];
i++;
}
pic->comments[pic->commentCounter][i] = '\0';
pic->commentCounter++;
}
/*
* Loading the max color property of the file which is gonna be 3 letters (Usually 255)
* and checking if we previously got maxColors in our construct or not. If we didn't
* then we load this value into the consturct and the condition will never validate
* throughout the iterations
*/
if(strlen(line) == 3 && pic->maxColors == 0 && line[0] != '#') {
pic->maxColors = atoi(line);
continue;
}
/*
* Check if the length of string > 3, which means it is going to be a
* number, potentially RGB value or a comment. But since width & height
* comes before RGB values, our condition will fail once we have found
* the width/height for the next iteration. That's why this condition
* only checks if it is a comment or a numbered value of length > 3
*/
if((strlen(line) > 3) && (pic->width == 0) && (line[0] != '#')) {
char *width = strtok(line, " ");
char *height = strtok(NULL, " ");
pic->width = atoi(width);
pic->height = atoi(height);
continue;
}
/*
* If the width/height and maxColors have been found, that means every
* other line is either going to be the RGB values or a comment.
*/
if((pic->width != 0) && (pic->maxColors != 0) && (line[0] != '#')) {
// length(line) > 3 means all the RGB values are in same line
if(strlen(line) > 3) {
char *val1 = strtok(line, " ");
char *val2 = strtok(NULL, " ");
char *val3 = strtok(NULL, " ");
// pixelsCounter = 0 means it's the first element.
if(pixelsCounter != 0) {
// Reallocate memory each time a new R G B value line is found
pic->pixelValues = realloc(pic->pixelValues, (pixelsCounter + 1) * sizeof(PPM));
}
pic->pixelValues[pixelsCounter] = malloc(12 * sizeof(pixels));
pic->pixelValues[pixelsCounter]->r = atoi(val1);
pic->pixelValues[pixelsCounter]->g = atoi(val2);
pic->pixelValues[pixelsCounter]->b = atoi(val3);
pixelsCounter++;
} else if(strlen(line) <= 3) {
/*
* If each individual RGB values are in a separete lines, we will
* use a switch case and a line counter to keep track of where the
* values were inserted and when to know when we got RGB values for
* one pixel
*/
if(pixelsCounter != 0 && lineCounter == 0) {
// Reallocate memory each time a new R G B value line is found
pic->pixelValues = realloc(pic->pixelValues, (pixelsCounter + 1) * sizeof(PPM));
}
switch(lineCounter) {
case 0 :
pic->pixelValues[pixelsCounter] = malloc(12 * sizeof(pixels));
pic->pixelValues[pixelsCounter]->r = atoi(line);
lineCounter++;
continue;
case 1 :
pic->pixelValues[pixelsCounter]->g = atoi(line);
lineCounter++;
continue;
case 2 :
pic->pixelValues[pixelsCounter]->b = atoi(line);
lineCounter=0;
pixelsCounter++;
continue;
default:
continue;
}
}
}
}
pic->pixelValues[pixelsCounter] = NULL;
fclose(f);
return pic;
}
void showPPM(PPM * im) {
printf("%s\n",im->format);
int k = 0;
while(k < im->commentCounter) {
printf("%s\n", im->comments[k]);
k++;
}
printf("%d %d\n", im->width, im->height);
printf("%d\n",im->maxColors);
int j = 0;
while(im->pixelValues[j] != NULL) {
printf("%d %d %d\n", im->pixelValues[j]->r, im->pixelValues[j]->g, im->pixelValues[j]->b);
j++;
}
}
PPM *encode(PPM *im, char *message, unsigned int mSize, unsigned int secret) {
int *binaryMessage = decimalToBinary(message, mSize);
int i, j = 0, lineCounter = 0;
for(i = 0; i < 40; i++) {
switch(lineCounter) {
case 0 :
im->pixelValues[j]->r |= binaryMessage[i] << 0;
lineCounter++;
continue;
case 1 :
im->pixelValues[j]->g |= binaryMessage[i] << 0;
lineCounter++;
continue;
case 2 :
im->pixelValues[j]->b |= binaryMessage[i] << 0;
lineCounter=0;
j++;
continue;
default:
continue;
}
}
return im;
}
/*
* Converts a string into binary to be used in encode function. It
* first converts each letter of the string into ascii code. Then
* finds and stores each of the 8 bits of that int (ascii code of
* the letter) sequentially in an array.
*/
static int *decimalToBinary(const char *message, unsigned int length) {
/*
* malloc is used here instead of [] notation to allocate memory,
* because defining the variable with [] will make its scope
* limited to this function only. Since we want to access this
* array later on, we use malloc to assign space in the memory
* for it so we can access it using a pointer later on.
*/
int k=0, i, j;
unsigned int c;
unsigned int *binary = malloc(8 * length);
for(i = 0; i < length; i++) {
c = message[i];
for(j = 7; j >= 0; j--,k++) {
/*
* We check here if the jth bit of the number is 1 or 0
* using the bit operator &. If it is 1, it will return
* 1 because 1 & 1 will be true. Otherwise 0.
*/
if((c >> j) & 1)
binary[k] = 1;
else
binary[k] = 0;
}
}
return binary;
}
PPM файл:
P3
# CREATOR: GIMP PNM Filter Version 1.1
# Amazing comment 2
# Yet another amazing comment
400 530
255
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0