[C] Compiler error while using functions

Scupham · 12-09-2008, 03:12 AM

I am getting a compiler error which is preventing me from completing my program.

If i can get the one error out it should solve all of the others.

ALL ERRORS ARE IN BOLD SECTION OF CODE

Errors

Quote:

J:\test\test.c(101) : error C2143: syntax error : missing ';' before 'type'
J:\test\test.c(104) : error C2143: syntax error : missing ';' before 'type'
J:\test\test.c(111) : error C2065: 'sumx' : undeclared identifier
J:\test\test.c(111) : warning C4244: '+=' : conversion from 'double ' to 'int ', possible loss of data
J:\test\test.c(112) : error C2065: 'sumy' : undeclared identifier
J:\test\test.c(112) : warning C4244: '+=' : conversion from 'double ' to 'int ', possible loss of data
J:\test\test.c(113) : error C2065: 'sumxx' : undeclared identifier
J:\test\test.c(113) : warning C4244: '+=' : conversion from 'double ' to 'int ', possible loss of data
J:\test\test.c(114) : error C2065: 'sumxy' : undeclared identifier
J:\test\test.c(114) : warning C4244: '+=' : conversion from 'double ' to 'int ', possible loss of data
J:\test\test.c(116) : error C2065: 'n' : undeclared identifier
J:\test\test.c(120) : error C2065: 'line_parameters_ptr' : undeclared identifier
J:\test\test.c(120) : error C2223: left of '->gradient' must point to struct/union
J:\test\test.c(121) : error C2223: left of '->constant' must point to struct/union
Error executing cl.exe.

test.obj - 10 error(s), 4 warning(s)

Code:

Quote:

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

struct filenames
{
char measurements_filename[101] ;
char line_parameters_filename[101];
};

struct measurements
{
double x,y;
struct measurements *next;
};

struct line_parameters
{
double gradient, constant;
struct line_parameters *next;
};

int main (void)
{
struct filenames filenames, *filenames_ptr;
struct measurements measurements, *measurement_ptr;
struct line_parameters line_parameters, *line_parameters_ptr;

void get_filenames(struct filenames *);
void read_measurments(struct filenames*, struct measurements *);
void calculate_line_parameters(struct measurements*, struct line_parameters * );
void write_line_parameters(struct filenames, struct line_parameters );

filenames_ptr = &filenames;
measurement_ptr= &measurements;
line_parameters_ptr= &line_parameters;

get_filenames(filenames_ptr);
fprintf(stdout, "%s\n",filenames_ptr->measurements_filename);
fprintf(stdout, "%s\n",filenames_ptr->line_parameters_filename);

read_measurments(filenames_ptr, measurement_ptr);
calculate_line_parameters(measurement_ptr, line_parameters_ptr);
write_line_parameters(filenames, line_parameters);
return(0);
}

void get_filenames(struct filenames *filenames_ptr)
{
fprintf(stdout, "Enter file name:\n");
fscanf(stdin, "%s",filenames_ptr->measurements_filename);

fprintf(stdout, "Enter file name to Save to:\n");
fscanf(stdin, "%s",filenames_ptr->line_parameters_filename);
return;
}

void read_measurments(struct filenames *filenames_ptr, struct measurements *measurement_ptr)
{
char line[101];
char *line_ptr;
int no_values=0;
struct measurements *current_measurements_ptr=measurement_ptr, *new_measurements_ptr;
FILE *input_stream;
input_stream=fopen(filenames_ptr->measurements_filename, "r");

if(input_stream!=NULL)
{
fprintf(stdout, "File found!\n");
fgets(line,sizeof(line), input_stream);

while (((line_ptr=fgets(line,sizeof(line), input_stream))!=NULL) && ((no_values= sscanf(line,"%lf %lf",
&current_measurements_ptr->x,
&current_measurements_ptr->y))==2))
{
current_measurements_ptr -> next=(struct measurements*)malloc(sizeof(struct measurements));
if (measurement_ptr!=NULL)
{
current_measurements_ptr=current_measurements_ptr -> next;
current_measurements_ptr -> next= NULL;
}

}
fclose(input_stream);
return;
}

void calculate_line_parameters(struct measurements *measurement_ptr, struct line_parameters *line_parameters_ptr)
{
struct measurements *measurement_ptr=NULL, *current_measurements_ptr;
double sumx=0, sumy=0, sumxx=0, sumxy=0, n=0;

current_measurements_ptr = new_measurements_ptr ;

while(current_measurements_ptr->next != NULL)
{

sumx += measurement_ptr->x;
sumy += measurement_ptr->y;
sumxx += (measurement_ptr->x) * (measurement_ptr->x);
sumxy += (measurement_ptr->x) * (measurement_ptr->y);

n ++;
current_measurements_ptr = current_measurements_ptr->next;
}

line_parameters_ptr->gradient = ((n * sumxy)-(sumx * sumy))/((n * sumxx)-(sumx * sumx));
line_parameters_ptr->constant = ((sumxy * sumx) - (sumxx * sumy)) / ((sumx * sumx) -(n * sumxx));
fprintf(stdout, "lol WIN!");
return;
}

void write_line_parameters(struct filenames filenames, struct line_parameters line_parameters)
{
FILE *output_stream;
output_stream = fopen(filenames.line_parameters_filename, "w");

fprintf(output_stream, "%lf \n", line_parameters.gradient);
fprintf(output_stream, "%lf \n", line_parameters.constant);

fclose(output_stream);
return;
}

Thanks for your time

matsp · 12-09-2008, 03:21 AM

If you indent your code properly, then you will see that you are missing a end-brace, which causes the compiler to get completely lost. The compiler doesn't care about indentation, but humans do!

--
Mats

Scupham · 12-09-2008, 03:26 AM

Ok changed that thanks

JoeBloggs · 12-09-2008, 03:28 AM

Code:

void read_measurments(struct filenames *filenames_ptr, struct measurements *measurement_ptr)
{
char line[101];
char *line_ptr;
int no_values=0;
struct measurements *current_measurements_ptr=measurement_ptr, *new_measurements_ptr;
FILE *input_stream;
input_stream=fopen(filenames_ptr->measurements_filename, "r");

if(input_stream!=NULL)
{
fprintf(stdout, "File found!\n");
fgets(line,sizeof(line), input_stream);

while (((line_ptr=fgets(line,sizeof(line), input_stream))!=NULL) && ((no_values= sscanf(line,"%lf %lf",
&current_measurements_ptr->x,
&current_measurements_ptr->y))==2))
{
current_measurements_ptr -> next=(struct measurements*)malloc(sizeof(struct measurements));
if (measurement_ptr!=NULL)
{
current_measurements_ptr=current_measurements_ptr -> next;
current_measurements_ptr -> next= NULL;
}

}
fclose(input_stream);
return;
}
}

Bolded and underlined.

Scupham · 12-09-2008, 03:38 AM

EDIT: bolded wrong section, actually crashing at calculating data

Ok new issues.

I get the program crashing when i run, it seems to crash when im calculating the line parameters

Code:

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


struct filenames
	{
	char measurements_filename[101] ;
	char line_parameters_filename[101];
	};

struct measurements
	{
	double x,y;
	struct measurements *next;
	};

struct line_parameters
	{
	double gradient, constant;
	struct line_parameters *next;
	};



int main (void)
{
struct filenames filenames, *filenames_ptr;
struct measurements measurements, *measurement_ptr;
struct line_parameters line_parameters, *line_parameters_ptr;
	
	void get_filenames(struct filenames *);
	void read_measurments(struct filenames*, struct measurements *);
	void calculate_line_parameters(struct measurements*, struct line_parameters * );
	void write_line_parameters(struct filenames, struct line_parameters );

filenames_ptr = &filenames;
measurement_ptr= &measurements;
line_parameters_ptr= &line_parameters; 


get_filenames(filenames_ptr);
fprintf(stdout, "%sn",filenames_ptr->measurements_filename);
fprintf(stdout, "%sn",filenames_ptr->line_parameters_filename);

read_measurments(filenames_ptr, measurement_ptr);
calculate_line_parameters(measurement_ptr, line_parameters_ptr);
write_line_parameters(filenames, line_parameters);
return(0);
}




void get_filenames(struct filenames *filenames_ptr)
{
fprintf(stdout, "Enter file name:n");
fscanf(stdin, "%s",filenames_ptr->measurements_filename);

fprintf(stdout, "Enter file name to Save to:n");
fscanf(stdin, "%s",filenames_ptr->line_parameters_filename);
return;
}




void read_measurments(struct filenames *filenames_ptr, struct measurements *measurement_ptr)
{
char line[101];
char *line_ptr;
int no_values=0;
struct measurements *current_measurements_ptr=measurement_ptr;
FILE *input_stream;
input_stream=fopen(filenames_ptr->measurements_filename, "r");

if(input_stream!=NULL)
		{
		fprintf(stdout, "File found!n");
		fgets(line,sizeof(line), input_stream);
			
			while (((line_ptr=fgets(line,sizeof(line), input_stream))!=NULL) && ((no_values= sscanf(line,"%lf %lf",
										&current_measurements_ptr->x,
										&current_measurements_ptr->y))==2))
			{
			current_measurements_ptr -> next=(struct measurements*)malloc(sizeof(struct measurements));		
				if (measurement_ptr!=NULL)
				{
				current_measurements_ptr=current_measurements_ptr -> next;
				current_measurements_ptr -> next= NULL;
				}	
			
			}
}	
fclose(input_stream);
return;
}
				


void calculate_line_parameters(struct measurements *measurements, struct line_parameters *line_parameters_ptr)

{
struct measurements *measurement_ptr=NULL, *current_measurements_ptr;

double sumx=0, sumy=0, sumxx=0, sumxy=0, n=0;

current_measurements_ptr = measurements;

while(current_measurements_ptr->next != NULL)
	{

	sumx  +=  measurement_ptr->x;
	sumy  +=  measurement_ptr->y;
	sumxx += (measurement_ptr->x) * (measurement_ptr->x);
	sumxy += (measurement_patr->x) * (measurement_ptr->y);
	
	n ++;
	current_measurements_ptr = current_measurements_ptr->next;
	}

line_parameters_ptr->gradient = ((n * sumxy)-(sumx * sumy))/((n * sumxx)-(sumx * sumx));
line_parameters_ptr->constant = ((sumxy * sumx) - (sumxx * sumy)) / ((sumx * sumx) -(n * sumxx));
	fprintf(stdout, "lol WIN");
return;
}



void write_line_parameters(struct filenames filenames, struct line_parameters line_parameters)
{
FILE *output_stream;
output_stream = fopen(filenames.line_parameters_filename, "w");
	
fprintf(output_stream, "%lf n", line_parameters.gradient);
fprintf(output_stream, "%lf n", line_parameters.constant);

fclose(output_stream);
return;
}

Any ideas?

Elysia · 12-09-2008, 04:05 AM

Indent the code. You were told before.
UPDATE:

Code:

sumx += measurement_ptr->x;
sumy += measurement_ptr->y;
sumxx += (measurement_ptr->x) * (measurement_ptr->x);
sumxy += (measurement_patr->x) * (measurement_ptr->y);

measurement_ptr is uninitialized.
Heed your compiler warnings!
If none are shown, enable max warnings.
Project properties -> C/C++ -> General -> Warnings -> Set to level 4.
You can also launch your program through the debugger. It will break at things such as using an unitialized variable (default hotkey: F5, though it may vary with keyboard scheme).

matsp · 12-09-2008, 04:09 AM

Is the first line of your input not used?

I take it you don't actually want to use the last measurement, right?

--
Mats

mindagap · 12-09-2008, 06:25 PM

the program will run without errors and warnings, but it would not run properly.

12-09-2008, 03:21 AM	#2
matsp Kernel hacker Join Date: Jul 2007 Location: Farncombe, Surrey, England Posts: 15,686	If you indent your code properly, then you will see that you are missing a end-brace, which causes the compiler to get completely lost. The compiler doesn't care about indentation, but humans do! -- Mats __________________ Compilers can produce warnings - make the compiler programmers happy: Use them! Please don't PM me for help - and no, I don't do help over instant messengers.
matsp is offline

12-09-2008, 03:26 AM	#3
Scupham Registered User Join Date: Dec 2008 Posts: 19	Ok changed that thanks
Scupham is offline

12-09-2008, 04:09 AM	#7
matsp Kernel hacker Join Date: Jul 2007 Location: Farncombe, Surrey, England Posts: 15,686	Is the first line of your input not used? I take it you don't actually want to use the last measurement, right? -- Mats __________________ Compilers can produce warnings - make the compiler programmers happy: Use them! Please don't PM me for help - and no, I don't do help over instant messengers.
matsp is offline

12-09-2008, 06:25 PM	#8
mindagap Registered User Join Date: Dec 2008 Posts: 1	the program will run without errors and warnings, but it would not run properly.
mindagap is offline

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