trjhtr

I am working on a program that is meant to fold a large input line into smaller ones. Basic flow of the program would be as follows:

• User calls the program with a long string as input


• Program prints tokens generated in separate lines

I haven't seen handling file input yet, so keep that in mind. I haven't seen reading input from the command line either.

Here's the source code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int length(char input);

int main(int argc, char* argv)


 if(argc < 3)
 
 printf("Usage: %s input [n]n", argv[0]);
 exit(1);
 

 int COL_BOUND = atof(argv[2]);

 int startCol, currentCut, nextBound, numOfCuts;

 startCol = currentCut = nextBound = numOfCuts = 0;

 //while the next bound is still "inside" string
 while((nextBound = startCol + COL_BOUND - 1) <= length(argv[1]))
 

 //print remaining characters
 int printed = 0;
 ++numOfCuts;
 for(int i=startCol; i <= length(argv[1]); ++i)
 
 if(isspace(argv[1][i]) && printed == 0)
 continue;
 ++printed;
 putchar(argv[1][i]);
 

 printf("nOriginal string split into %d parts (bound was %d)n", numOfCuts, COL_BOUND);
 return 0;


int length(char input)

 int i;
 for(i=0; input[i] != ''; ++i)
 ;
 return i;

The length() function can be replaced using strlen() (you'll need to include <string.h>). Note that strlen() doesn't consider the terminating NUL to be part of the string - but that will help fix the current bug that causes this code to print that NUL.

Don't measure the length repeatedly - instead, save it to a variable early on, and refer to that variable.

Error messages should go to standard error stream, not standard output:

if (argc < 3) 
 fprintf(stderr, "Usage: %s input colsn", argv[0]);
 return 1;

Don't use uppercase names for variables - we reserve those for macros; the "SHOUTING" of the name warns us that they need special care.

Also, don't use atof() for converting integers - use atoi(), or better, strtoul(), which can tell you whether it succeeded:

char *parse_end;
size_t col_bound = strtoul(argv[2], &parse_end, 10);
if (parse_end == argv[2] || *parse_end) 
 fprintf(stderr, "Usage: %s input colsn", argv[0]);
 return 1;

Prefer one declaration per line, and initialise immediately:

size_t startCol = 0;
size_t currentCut = 0;
size_t nextBound = 0;
size_t numOfCuts = 0;

Be careful about off-by-one errors. This inequality should be <, not <=:

while ((nextBound = startCol + col_bound - 1) < length) {

It's not the only one.

Test more inputs. I tried a very simple case and got unexpected output:

./194156 'a b c d e f' 3

a b
c
d e
f
Original string split into 4 parts(bound was 3)

Why did it not split into 3 lines?