fprintf(3C)
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fprintf function
Perform a formatted write to a file.
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Calling Sequence
#include <stdio.h>
FILE *fp;
int fprintf();
char *format;
fprintf(fp, format, arg ...);
where
fp is a pointer to the output FILE stream.
format is a string containing two kinds of objects:
ASCII characters that the function copies directly.
Conversion specifications that start with %.
Each arg is a valid C variable or constant.
Description
The fprintf function enables you to write to a file. It replaces
the format specifications with the successive argument(s) (arg
...) and writes the result to a file. For details about
conversion specifications, see the printf function.
Returns
The fprintf function returns -1 if an error occurs. Otherwise,
it returns the number of characters in the output.
Related Functions
See also the fscanf, printf, and sprintf functions.
Example
/* Program test for the fprintf() function */
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fprintf(3C)
#include <stdio.h>
FILE *fp, *fopen();
int i = 2, ibuf, atoi(), fprintf();
double dbuf, atof();
main(argc, argv)
int argc;
char *argv[];
{
fp = fopen(argv[1], "a");
fprintf(fp, "This program prints numerical data to a\n");
fprintf(fp, "file in a variety of formats.\n\n");
while (i < argc) {
dbuf = atof(argv[i]);
fprintf(fp, "%e in scientific notation =\n", dbuf);
fprintf(fp, "%f in normal notation =\n", dbuf);
ibuf = atoi(argv[i]);
fprintf(fp, "%d decimal =\n%o octal =\n", ibuf, ibuf);
fprintf(fp, "%x hexadecimal.\n\n",ibuf);
i++;
}
}
A call to the program test with the valid filename result_nos
(which is empty) and the input numbers
144
3.1416
-99.99e4
generates in the file result_nos the output
This program prints numerical data to a
file in a variety of formats.
1.440000e+02 in scientific notation =
144.000000 in normal notation =
144 decimal =
220 octal =
90 hexadecimal.
3.141600e+00 in scientific notation =
3.141600 in normal notation =
3 decimal =
3 octal =
3 hexadecimal.
-9.999000e+05 in scientific notation =
-999900.000000 in normal notation =
-99 decimal =
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fprintf(3C)
37777777635 octal =
ffffff9d hexadecimal.
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