Question

Question:

For the picture writing question, if the question says that the
picture length (height) and width are multiples of 5, then be prepared 
(for example) to handle a situation where you are being asked to blacken 
the fourth (vertical) strip  from the left.

Code:

#include
#include
#include
#include

#define BUFFER_SIZE 70
#define TRUE 1
#define FALSE 0

int** img;
int numRows;
int numCols;
int maxVal;
FILE* fo1;

void addtopixels(int** imgtemp, int value);
void writeoutpic(char* fileName, int** imgtemp);
int** readpic(char* fileName);
void readHeader(FILE* imgFin);
int isComment(char* line);
void readImgID(char* line);
void readImgSize(char* line);
void readMaxVal(char* line);
int** setImage();
void readBinaryData(FILE* imgFin, int** imgtemp);

int main()
{
char fileName[BUFFER_SIZE];
int i,j,rows,cols;
char ci;

printf("Enter image filename: ");
scanf("%s", fileName);

img = readpic(fileName);

printf("Successfully read image file '%s'\n", fileName);

addtopixels(img,103);

printf("Enter image filename for output: ");
scanf("%s", fileName);

writeoutpic(fileName,img);

free(img);
img = NULL;

return(EXIT_SUCCESS);
}

void addtopixels(int** imgtemp, int value)
{
int i,j;
  
for (i=0;i { for (j=0;j {
imgtemp[numCols-1-i][numRows-1-j] = imgtemp[i][j];
}
}
}

void writeoutpic(char* fileName, int** imgtemp)
{
int i,j;
char ci;
FILE* fo1;
  
if((fo1 = fopen(fileName, "wb")) == NULL)
{
printf("Unable to open out image file '%s'\n", fileName);
exit(EXIT_FAILURE);
}

fprintf(fo1,"P5\n");
fprintf(fo1,"%d %d\n", numRows, numCols);
fprintf(fo1,"255\n");

for (i=0;i { for (j=0;j {
ci = (char) (imgtemp[i][j]);
fprintf(fo1,"%c", ci);
}
}
}

int** readpic(char* fileName)
{
FILE* imgFin;
int** imgtemp;

if((imgFin = fopen(fileName, "rb")) == NULL)
{
printf("Unable to open image file '%s'\n", fileName);
exit(EXIT_FAILURE);
}

readHeader(imgFin);

imgtemp = setImage();

readBinaryData(imgFin, imgtemp);

fclose(imgFin);
  
return imgtemp;

}

void readHeader(FILE* imgFin)
{
int haveReadImgID = FALSE;
int haveReadImgSize = FALSE;
int haveReadMaxVal = FALSE;
char line[BUFFER_SIZE];

while(!(haveReadImgID && haveReadImgSize && haveReadMaxVal))
{
fgets(line, BUFFER_SIZE, imgFin);

if((strlen(line) == 0) || (strlen(line) == 1))
continue;

if(isComment(line))
continue;

if(!(haveReadImgID))
{
readImgID(line);
haveReadImgID = TRUE;
}
else if(!(haveReadImgSize))
{
readImgSize(line);
haveReadImgSize = TRUE;
}
else if(!(haveReadMaxVal))
{
readMaxVal(line);
haveReadMaxVal = TRUE;
}
}

}

int isComment(char *line)
{
if(line[0] == '#')
return(TRUE);

return(FALSE);
}

void readImgID(char* line)
{
if(strcmp(line, "P5\n") != 0)
{
printf("Invalid image ID\n");
exit(EXIT_FAILURE);
}
}

void readImgSize(char* line)
{
unsigned i;

for(i = 0; i < strlen(line); ++i)
{
if(!((isdigit((int) line[i])) || (isspace((int) line[i]))))
{
printf("Invalid image size\n");
exit(EXIT_FAILURE);
}
}

sscanf(line, "%d %d", &numRows, &numCols);
}

void readMaxVal(char* line)
{
unsigned i;

for(i = 0; i < strlen(line); ++i)
{
if(!((isdigit((int) line[i])) || (isspace((int) line[i]))))
{
printf("Invalid image max value\n");
exit(EXIT_FAILURE);
}
}

maxVal = atoi(line);
}

int** setImage()
{
int** imgtemp;
unsigned i;

imgtemp = (int**) calloc(numRows, sizeof(int*));

for(i = 0; i < numRows; ++i)
{
imgtemp[i] = (int*) calloc(numCols, sizeof(int));
}
return imgtemp;
}

void readBinaryData(FILE* imgFin, int** imgtemp)
{
unsigned i;
unsigned j;
for(i = 0; i < numRows; ++i)
{
for(j = 0; j < numCols; ++j)
{
imgtemp[i][j] =
fgetc(imgFin);
}
}
}

ONLY THIS PART MUST BE EDITED (PLEASE GIVE THIS EDITED PART AS THE SOLUTION):

void addtopixels(int** imgtemp, int value)
{
int i,j;
  
for (i=0;i { for (j=0;j {
imgtemp[numCols-1-i][numRows-1-j] = imgtemp[i][j];
}
}
}

Answer 1

void addtopixels(int** imgtemp, int value)
{
   int x = numCols / 5;
   int a = x * 3;
   int b = x * 4;
   int i, j;
   for (i = 0; i < numRows; ++i)
   {
       for (j = 0; j < numCols; ++j)
       {
           if (j >= a && j < b)
               imgtemp[i][j] += value;
       }
   }
}

// also this function of yours seemed to have syntax errors, i fixed it for you.

void writeoutpic(char* fileName, int** imgtemp)
{
   int i, j;
   char ci;
   FILE* fo1;

   if ((fo1 = fopen(fileName, "wb")) == NULL)
   {
       printf("Unable to open out image file '%s'\n", fileName);
       exit(EXIT_FAILURE);
   }

   fprintf(fo1, "P5\n");
   fprintf(fo1, "%d %d\n", numRows, numCols);
   fprintf(fo1, "255\n");

// errors were below this comment

   for (i = 0; i < numRows; ++i)
   {
       for (j = 0; j < numCols; ++j)
       {
           ci = (char)(imgtemp[i][j]);
           fprintf(fo1, "%c", ci);
       }
   }
}

//test case

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