我发现堆栈溢出代码可以执行此操作，但我在使用它时遇到了一些错误。我不确定我做错了什么，因为我对ppm文件没有多少经验。谢谢大家的帮助。
typedef struct {
int x, y;
PPMPixel *data;
} PPMImage;
#define CREATOR "RPFELGUEIRAS"
#define RGB_COMPONENT_COLOR 255
static PPMImage *readPPM(const char *filename = "ukraine.ppm")
{
char buff[16];
PPMImage *img;
FILE *fp;
int c, rgb_comp_color;
//open PPM file for reading
fp = fopen("ukraine.ppm", "rb");
if (!fp) {
fprintf(stderr, "Unable to open file '%s'\n", filename);
exit(1);
}
//read image format
if (!fgets(buff, sizeof(buff), fp)) {
perror(ukraine.ppm);
exit(1);
}
//check the image format
if (buff[0] != 'P' || buff[1] != '6') {
fprintf(stderr, "Invalid image format (must be 'P6')\n");
exit(1);
}
//alloc memory form image
img = (PPMImage *)malloc(sizeof(PPMImage));
if (!img) {
fprintf(stderr, "Unable to allocate memory\n");
exit(1);
}
//check for comments
c = getc(fp);
while (c == '#') {
while (getc(fp) != '\n') ;
c = getc(fp);
}
ungetc(c, fp);
//read image size information
if (fscanf(fp, "%d %d", &img->x, &img->y) != 2) {
fprintf(stderr, "Invalid image size (error loading '%s')\n", ukraine.ppm);
exit(1);
}
//read rgb component
if (fscanf(fp, "%d", &rgb_comp_color) != 1) {
fprintf(stderr, "Invalid rgb component (error loading '%s')\n", filename);
exit(1);
}
//check rgb component depth
if (rgb_comp_color!= RGB_COMPONENT_COLOR) {
fprintf(stderr, "'%s' does not have 8-bits components\n", filename);
exit(1);
}
while (fgetc(fp) != '\n') ;
//memory allocation for pixel data
img->data = (PPMPixel*)malloc(img->x * img->y * sizeof(PPMPixel));
if (!img) {
fprintf(stderr, "Unable to allocate memory\n");
exit(1);
}
//read pixel data from file
if (fread(img->data, 3 * img->x, img->y, fp) != img->y) {
fprintf(stderr, "Error loading image '%s'\n", filename);
exit(1);
}
fclose(fp);
return img;
}
void writePPM(const char *filename = "ukraine.ppm", PPMImage *img)
{
FILE *fp;
//open file for output
fp = fopen(ukraine.ppm, "wb");
if (!fp) {
fprintf(stderr, "Unable to open file '%s'\n",filename);
exit(1);
}
//write the header file
//image format
fprintf(fp, "P6\n");
//comments
fprintf(fp, "# Created by %s\n",CREATOR);
//image size
fprintf(fp, "%d %d\n",img->x,img->y);
// rgb component depth
fprintf(fp, "%d\n",RGB_COMPONENT_COLOR);
// pixel data
fwrite(img->data, 3 * img->x, img->y, fp);
fclose(fp);
}
void changeColorPPM(PPMImage *img)
{
int i;
if(img){
for(i=0;i<img->x*img->y;i++){
img->data[i].red=RGB_COMPONENT_COLOR-img->data[i].red;
img->data[i].green=RGB_COMPONENT_COLOR-img->data[i].green;
img->data[i].blue=RGB_COMPONENT_COLOR-img->data[i].blue;
}
}
}
int main(){
PPMImage *image;
image = readPPM("can_bottom.ppm");
changeColorPPM(image);
writePPM("can_bottom2.ppm",image);
printf("Press any key...");
getchar();
return(0);
}
错误消息
[21:47:34] cehutto@hornet6:~/101/lab12 [8] gcc imageChange.c imageChange.c:18:47: error: expected â;â, â,â or â)â before â=â token
imageChange.c:94:36: error: expected â;â, â,â or â)â before â=â token
imageChange.c: In function âmainâ: imageChange.c:137:11: warning: assignment makes pointer from integer without a cast [enabled by default]
[21:47:34] cehutto@hornet6:~/101/lab12 [9] Last login: Tue Apr 14 21:28:19 2015 from 48.253.21.198.tigernet.wifi.dyn.clemson.edu
[23:42:52] cehutto@hornet6:~ [1]`
答案 0 :(得分：-1)
以下代码干净地编译。
它是硬编码的文件ukraine.ppm
您可以轻松修改文件以使用文件全局字符数组
输入文件的主要设置
您可以轻松修改文件以使用文件全局字符数组
输出文件的主要设置
#include <stdio.h>
#include <stdlib.h>
struct PPMPixel
{
char red;
char blue;
char green;
};
struct PPMImage
{
unsigned x, y;
struct PPMPixel *data;
};
#define CREATOR "RPFELGUEIRAS"
#define RGB_COMPONENT_COLOR (255)
static struct PPMImage *readPPM()
{
char buff[16];
struct PPMImage *img;
FILE *fp;
int c;
int rgb_comp_color;
//open PPM file for reading
fp = fopen("ukraine.ppm", "rb");
if (!fp)
{
perror( "fopen for ukraine.ppm failed" );
// fprintf(stderr, "Unable to open file '%s'\n", filename);
exit(1);
}
// implied els,e fopen successful
//read image format // get first 15 bytes of image file
if (!fgets(buff, sizeof(buff), fp))
{
perror("ukraine.ppm");
exit(1);
}
// implied else, fgets successful
//check the image format
if (buff[0] != 'P' || buff[1] != '6') {
fprintf(stderr, "Invalid image format (must be 'P6')\n");
exit(1);
}
// implied else, image file file has correct format indicators
//alloc memory for image
img = malloc(sizeof(struct PPMImage));
if (!img)
{
perror( "malloc for PPMImage failed" );
//fprintf(stderr, "Unable to allocate memory\n");
exit(1);
}
// implied else, malloc successful
//check for comments
c = getc(fp);
while (c == '#')
{
while( (c = getc(fp)) != '\n') ;
}
//read image size information
if (fscanf(fp, "%u %u", &img->x, &img->y) != 2)
{
perror( "fscanf for ukraine.ppm image size parameters failed" );
exit(1);
}
// implied else, fscanf successful
//read rgb component
if (fscanf(fp, "%d", &rgb_comp_color) != 1)
{
perror( "fscanf for rgb_comp_color in ukraine.ppm failed" );
//fprintf(stderr, "Invalid rgb component (error loading '%s')\n", filename);
exit(1);
}
// implied else, fscanf successful
//check rgb component depth
if (rgb_comp_color!= RGB_COMPONENT_COLOR)
{
fprintf(stderr, "'ukraine.ppm' does not have 8-bits components\n");
exit(1);
}
// implied else, rgb component depth correct
// consume rest of line
while (fgetc(fp) != '\n') ;
//memory allocation for pixel data
img->data = malloc(img->x * img->y * sizeof( struct PPMPixel));
if ( !img->data ) //< corrected element being checked
{
perror( "malloc for pixel data failed" );
//fprintf(stderr, "Unable to allocate memory\n");
exit(1);
}
// implied else, malloc successful
//read pixel data from file
if (fread(img->data, 3 * img->x, img->y, fp) != img->y)
{
perror( "fread for pixel data failed" );
// fprintf(stderr, "Error loading image '%s'\n", filename);
exit(1);
}
// implied else, fread successful
fclose(fp);
return img;
} // end function: readPPM
void writePPM(struct PPMImage *img)
{
FILE *fp;
//open file for output
fp = fopen("ukraine.ppm", "wb");
if (!fp)
{
perror( "fopen for ukraine.ppm for write failed" );
// fprintf(stderr, "Unable to open file '%s'\n",filename);
exit(1);
}
// implied else, fopen successful
//write the header file
//image format
fprintf(fp, "P6\n");
//comments
fprintf(fp, "# Created by %s\n",CREATOR);
//image size
fprintf(fp, "%d %d\n",img->x,img->y);
// rgb component depth
fprintf(fp, "%d\n",RGB_COMPONENT_COLOR);
// pixel data
fwrite(img->data, 3 * img->x, img->y, fp);
fclose(fp);
} // end function: writePPM
void changeColorPPM(struct PPMImage *img)
{
unsigned i;
if(img)
{
for(i=0;i<img->x*img->y;i++)
{
img->data[i].red=RGB_COMPONENT_COLOR-img->data[i].red;
img->data[i].green=RGB_COMPONENT_COLOR-img->data[i].green;
img->data[i].blue=RGB_COMPONENT_COLOR-img->data[i].blue;
}
}
} // end function: changeColorPPM
int main()
{
struct PPMImage *image;
image = readPPM();
changeColorPPM(image);
writePPM(image);
printf("Press any key...");
getchar();
return(0);
} // end function: main