Why does fscanf ignore the first string? - c

Question

I am trying to make a translator.
This is the part where I put all the strings from the text file on the memory.
But the program ignores the first string of the text file.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct b
{
char b[30];
}b;
int main()
{
int d,c,i=0;
char k[30],x;
b *a;
FILE *fp;
if ((fp=fopen("translate.txt","r"))==NULL)
{
printf("Σφάλμα κατά το άνοιγμα του αρχείου\n");
}
else
{
while(!feof(fp))
{
fscanf(fp,"%s",k);
i++;
}
a=malloc((i)*(sizeof(b)));
fclose(fp);
}
if ((fp=fopen("translate.txt","r+"))==NULL)
{
printf("Σφάλμα κατά το άνοιγμα του αρχείου\n");
}
else
{
rewind(fp);
for (c=0;c<i;c++)
{
fscanf(fp,"%s",a[c].b);
}
fclose(fp);
}

Answer 1

1. You should write this loop (so as to check return of fscanf ) —
for (c=0;c<i;c++)
{
fscanf(fp,"%s",a[c].b);
}
as —
c=0;
while (fscanf(fp,"%29s",a[c].b) == 1 && c<i){
...
c++;
}
2. Also while(!feof(fp)) is wrong, so instead use fscanf to control the loop —
while (fscanf(fp,"%29s",k)==1)
i++;
Note — And, just to avoid confusion, give different names to your structure member and structure.

Answer 2

after applying all the comments, the resulting code is:
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main( void )
{
char **lines = NULL;
size_t lineCount = 0;
FILE *fp = NULL;
if ((fp=fopen("translate.txt","r"))==NULL)
{
perror("Σφάλμα κατά το άνοιγμα του αρχείου\n");
exit( EXIT_FAILURE );
}
char * inputBuf = NULL;
size_t inputLen = 0;
while( getline( &inputBuf, &inputLen, fp ) )
{
lineCount++;
char **tempLines = realloc( lines, (lineCount+1)*sizeof( char*) );
if( !tempLines )
{ // then realloc failed
perror( "realloc failed");
free( lines );
exit( EXIT_FAILURE );
}
lines = tempLines;
lines[lineCount] = strdup( inputBuf );
lineCount++;
}
fclose(fp);
free( lines );
return 0;
} // end function: main
however, this code is not very efficient as it repeatedly calls realloc()
To fix that, initially allocate enough room in lines[] for several lines, say 10, then keep a count of how many of those pointers are being used.
When all the allocated pointers are used and need to add another line, then double the allocation via realloc().