C 创建 PGM 图像的参数编号

问题描述

我必须用 C 语言为大学做一个任务。该程序以 pgm 格式创建图像。该程序编译成功，但是，我无法正确运行该程序。在 main 函数的开头，if 操作符需要 2 个 argc，但每次我尝试运行程序时，我只有一个 argc，我得到了结果

“错误：缺少或错误的参数，用法 a3 [图像文件]”

代码是：

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <math.h>

const double PI = 3.1415926535897932;

int** loadImage (const char *filename,int* width,int* height);
bool saveImage (const char *filename,int **pixels,const unsigned int width,const unsigned int height);

/* *** task (a) *** */

int normalize(int value) {
  return 0;    // Dummy return
}

/* *** task (b) *** */

int** createImage(unsigned int width,unsigned int height,int value){
  
  return NULL;    // Dummy return
}

/* *** task (c) *** */

void freeImage(int** pixels,unsigned int width,unsigned int height){
  
}

/* *** task (d) *** */

int** inverter (int **pixels,int width,int height)
{
  
  return NULL;    // Dummy return
}

/* *** task (e) *** */

int** laplace (int **pixels,int height)
{
  
  return NULL;    // Dummy return
}

/* *** task (f) *** */

int** rotate (int** pixels,int height,double angle,int background)
{

  return NULL;    // Dummy return
}

int main (int argc,char **argv)
{
  if (argc == 2)
  {
    int width=0,height=0;
    int **image = loadImage (argv[1],&width,&height);
    if (image != NULL)
    {
      int **image1 = inverter (image,width,height);
      int **image2 = laplace (image,height);
      int **image3 = rotate (image,height,150,128);

      saveImage ("image0.pgm",image,height);
      saveImage ("image1.pgm",image1,height);
      saveImage ("image2.pgm",image2,height);
      saveImage ("image3.pgm",image3,height);

      freeImage (image,height);
      freeImage (image1,height);
      freeImage (image2,height);
      freeImage (image3,height);
    }
  }
  else {
    printf ("Error: missing or bad parameters,usage a3 [imagefile]\n");
  }
  return 0;
}

/* *** Bild aus Datei laden *** */
int** loadImage (const char *filename,int* height)
{
  const char *delimiter = " \n\r\t";
  FILE *file = fopen (filename,"rt");
  int** pixels;
  bool isValid = true;

  if (file != NULL)
  {
    char line [80];
    int n = 0,params [3];

    if (fgets (line,80,file) == NULL) isValid = false;
    if (strlen (line) != 3 || strncmp (line,"P2",2)) isValid = false;
    while (isValid && fgets (line,file) != NULL)
    {
      if (strlen (line) <= 71)
      {
        if (line[0] == '#') continue;
        char *p = strtok (line,delimiter);
        while (isValid && p != NULL)
        {
          if (n < 3)
          {
            int a = atoi (p);
            if (a <= 0) {isValid = false;}
            else {params[n++] = a;}
          }
          else
          {
            if (n == 3)
            {
              if (params[2] != 255) {isValid = false;}
              else {
                pixels = createImage (params[0],params[1],0);
                *width = params[0];
                *height = params[1];
              }
            }
            if (n-3 < *width * *height)
            {
              int x = (n-3) % *width;
              int y = (n-3) / *width;
              int value = atoi (p);
              pixels[y][x] = normalize(value);
              n++;
            }
            else {isValid = false;}
          }
          p = strtok (NULL,delimiter);
        }
      }
      else { isValid = false;}
    }
    fclose (file);
    if (n-3 != *width * *height) {isValid = false;}
    if (!isValid) freeImage (pixels,*width,*height);
  }
  return isValid ? pixels : NULL;
}

/* *** Bild in Datei speichern *** */

bool saveImage (const char *filename,unsigned int height)
{
  FILE *file = fopen (filename,"wt");

  if (file != NULL && pixels != NULL)
  {
    fprintf (file,"P2\n");
    fprintf (file,"%d %d\n",height);
    fprintf (file,"%d\n",255);
    for (int y = 0; y < height; y++)
    {
      for (int x = 0; x < width; x++)
      {
        fprintf (file,pixels[y][x]);
      }
    }
    fclose (file);
    return true;
  }
  return false;
}

教授还说我们应该在 VSCode 的任务中添加以下参数：

"args": [
"-g","-std=c99","-Wall","${file}","-o","${fileDirname}/${fileBasenameNoExtension}","-lm"
],

解决方法

您的程序 a3.exe 需要一个参数，即文件名。要从命令行运行它，请输入

.\a3.exe YourFilename

将 YourFilename 替换为您要使用的实际文件名。