Help on while function

[raortega3]

this error message is coming up for this function:

while (points != EOF) 
	{
		fprintf("%lf %lf\n", x[i], y[i]);
		i++;
		points = scanf(out, "%lf%lf", x[i],y[i]);
	}

error C2440: 'function' : cannot convert from 'float' to 'const char *'


Can anyone help me please...

Thank you very much.

[raortega3]

Here is the program I am trying to write.

#include <stdio.h>
int get_corners (FILE *inp, double x[], double y[], int z);
int output_corners(FILE *inp, double x[], double y[], int z);
int main()
{
	FILE *inp;
	FILE *out;
	double x[7], y[7];
	int k;
	inp = fopen("file.txt", "r");
	out = fopen("out.txt", "w");
	k = get_corners(inp, x, y, 5);
	return (0);
}
 
int get_corners (FILE *inp, double x[], double y[], int z)
{
	int i = 0, points;
	printf("Display Corners\n\n");
	points = fscanf(inp, "&#37;lf %lf", &x[i], &y[i]);
	printf("***********\n");
	while (points != EOF) 
{

	printf("%.2lf , %.2lf\n", x[i], y[i]);
	i++;
	points = fscanf(inp, "%lf%lf", &x[i], &y[i]);
}
	printf("***********\n");
	return (i);
}
 
 
 
 
int output_corners(FILE *out, float x[],  float y[], int z)
{
	int i = 0, points;
	
	fprintf("Output Data\n");
	points = fprintf(out, "%lf %lf", x[i], y[i]);
	while (points != EOF) 
	{
		fprintf("%.2lf %.2lf\n", x[i], y[i]);
		i++;
		points = fprintf(out, "%lf%lf", x[i],y[i]);
	}

return (i);
}

[cas]

Three quick points:

1. Your output_corners() function definition doesn't match the prototype.
2. fprintf() takes a FILE* as the first argument. You're sometimes passing a char*. Either use printf() or specify the FILE*; you can use stderr and stdout, although the latter is equivalent to printf().
3. You should use %f to print out doubles, not %lf. %lf is correct for scanf(), but not printf() in C89.

[matsp]

while (points != EOF) 
	{
		fprintf("%lf %lf\n", x[i], y[i]);
		i++;
		points = scanf(out, "%lf%lf", x[i],y[i]);
	}

As stated, fprintf() takes a FILE * as the first argument.

It seems like "out" is superfluous on this function

--
Mats

[raortega3]

Thank you for your help.




I was able to get the program in this form:

#include <stdio.h>
int get_corners (FILE *inp, double x[], double y[], int z);
int output_corners(FILE *out, double x[], double y[], int z);
int poly_area(FILE *inp, double x[], double y[], int z);
int main()
{
	FILE *inp;
	FILE *out;
	
	double x[7], y[7];
	int k;
	
	
	inp = fopen("file.txt", "r");
	k = get_corners(inp, x, y, 5);
	
	
	out = fopen("out.txt", "w");
	k = output_corners(out, x, y, 5);
	
	return (0);
}
 
int get_corners (FILE *inp, double x[], double y[], int z)
{
	int i = 0, points;
	
points = fscanf(inp, "&#37;lf %lf", &x[i], &y[i]);
	for (i = 0; i < 5; i++);
{
	printf(inp, "%lf , %lf\n", x[i], y[i]);
	points = fscanf(inp, "%lf%lf", &x[i], &y[i]);
}

	return (i);
}
 
int output_corners(FILE *out, double x[], double y[], int z)
{
	int i = 0, points;
	//fprintf("Output Data\n");
	points = fprintf(out, "%lf %lf", x[i], y[i]);
	while (points != NULL) 
	{
	printf(out, "%lf %lf\n", x[i], y[i]);
	i++;
	points = fprintf(out, "%lf %lf", x[i],y[i]);
}

return (i);
}

it has no "c" errors but something is wrong with the values that it is returning.

The txt file has numbers such as 1 2 4 7 6 8 1... and it is returning something similar to : 1.0 2.0 -9235243500000000000000000.0 -92342340000000000000000.0

any ideas or help?

Thanks once again
1.0 2.0 -9000000000000000000000000000000000

[matsp]

Right %lf is the right form for scanf to read a double, but it's also the right form for printing a long double. Since long double isnt't what your data is, then you'll be printing "garbage".

Use %f for printing.

--
Mats

[Salem]

#include <stdio.h>
int get_corners(FILE * inp, double x[], double y[], int z);
int output_corners(FILE * out, double x[], double y[], int z);
int poly_area(FILE * inp, double x[], double y[], int z);
int main()
{
    FILE *inp;
    FILE *out;

    double x[7], y[7];
    int k;


    inp = fopen("file.txt", "r");
    k = get_corners(inp, x, y, 5);


    out = fopen("out.txt", "w");
    k = output_corners(out, x, y, 5);

    return (0);
}

int get_corners(FILE * inp, double x[], double y[], int z)
{
    int i = 0, points; /* you only ever assign points, test it as well */

    points = fscanf(inp, "%lf %lf", &x[i], &y[i]);
    for (i = 0; i < 5; i++);/* This ; will hurt you */
    {
        printf(inp, "%lf , %lf\n", x[i], y[i]);
        points = fscanf(inp, "%lf%lf", &x[i], &y[i]);
    }

    return (i);
}

int output_corners(FILE * out, double x[], double y[], int z)
{
    int i = 0, points;
    points = fprintf(out, "%lf %lf", x[i], y[i]);
    while (points != NULL) { /* NULL is not one of the return values */
        printf(out, "%lf %lf\n", x[i], y[i]);
        i++;
        points = fprintf(out, "%lf %lf", x[i], y[i]);
    }

    return (i);
}

First off, maximise the warning level of the compiler (or get gcc) and pay attention to what it says.
With your latest effort, there's plenty to fix

$ gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c: In function `get_corners':
foo.c:31: warning: passing arg 1 of `printf' from incompatible pointer type
foo.c: In function `output_corners':
foo.c:41: warning: ISO C90 does not support the `%lf' printf format
foo.c:41: warning: ISO C90 does not support the `%lf' printf format
foo.c:42: warning: comparison between pointer and integer
foo.c:43: warning: passing arg 1 of `printf' from incompatible pointer type
foo.c:45: warning: ISO C90 does not support the `%lf' printf format
foo.c:45: warning: ISO C90 does not support the `%lf' printf format
foo.c: At top level:
foo.c:38: warning: unused parameter 'z'
foo.c:24: warning: unused parameter 'z'