Why the hyphen(-) is not printed? - c

Question

#include<stdio.h>
#include<stdlib.h>
int main(int argc, char* argv[])
{
FILE* fp = fopen(argv[1],"r");
char* ptr;
int size;
while(1){
int scanfinteger = fscanf(fp,"%d",&size);
ptr = (char*)malloc((size+1)*sizeof(char));
if(scanfinteger != 1){
int result = fscanf(fp,"%s",ptr);
printf("ptr:[%s]\n",ptr);
if(result == EOF)
break;
}
}
return 0;
}
input_file(argv[1]) contains this
10 This
10 is
10 buffers
10 -
10 hi
10 -hello
my program's output
ptr: [This]
ptr: [is]
ptr: [buffers]
ptr: [10]
ptr: [hi]
ptr: [hello]
I can't understand why the hyphen gets consumed. Has someone had seen this issue?
Thank you!

Answer 1

If I may suggest a different solution, I would suggest you read lines and then parse the lines.
Perhaps something like this:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
int main(int argc, char* argv[])
{
// First make sure you have enough arguments
if (argc < 2)
{
printf("Need an argument!\n");
return 1;
}
// Open the file, and make sure we succeeded
FILE *fp = fopen(argv[1], "r");
if (fp == NULL)
{
printf("Failed to open the file %s: %s\n", argv[1], strerror(errno));
return 1;
}
// Now read the file, one line at a time
char line[100];
while (fgets(line, sizeof line, fp) != NULL)
{
// Now we have a line, attempt to parse it
int value;
char string[100];
if (sscanf(line, "%d %99s", &value, string) != 2)
{
printf("Failed to parse the current line\n");
break; // Break out of the loop
}
printf("Read value %d, string '%s'\n", value, string);
}
// All done, or we had an error (should probably check that)
// Anyway, close the file and end the program
fclose(fp);
}
The problem with your current code (which doesn't seem to be the actual code you run) is that you only read the string if the reading of the number fails.
What the problem is with your actual code, that produces that output, I don't know. But somehow it comes out of sync. This can be seen in that you for one line read the number as the string.