Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

Chapter 6 ■ Characters
We have simply added the statements that deal with the line numbers to the algorithm above.
We can easily add the code that deals with the line numbers to Program P6.10 to get Program
P6.11. Note that when we print the line number, we do not terminate the line with \n since the
data must be written on the same line as the line number.
Program P6.11
//This program prints the data from a file numbering the lines
#include <stdio.h>
int main() {
char ch;
FILE *in = fopen("input.txt", "r");
int lineNo = 1;
printf("%2d. ", lineNo);
while ((ch = getc(in)) != EOF) {
putchar(ch);
if (ch == '\n') {
lineNo++;
printf("%2d. ", lineNo);
}
}
fclose(in);
}
Assume the input file contains the following:
There was a little girl
Who had a little curl
Right in the middle of her forehead
Program P6.11 will print this:
1. There was a little girl
2. Who had a little curl
3. Right in the middle of her forehead
4.
Almost, but not quite, correct! The little glitch is that we print an extra line number at the end.
To see why, look at the if statement. When \n of the third data line is read, 1 would be added to
lineNo, making it 4, which is printed by the next statement. This printing of an extra line number
also holds if the input file is empty, since line number 1 would be printed in this case, but there is
no such line.
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