linefold.c - program that folds long input lines into shorter lines after first nonwhitespace character

linefold.c

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

// Write a program to fold long input lines into 2 shorter lines
// after first nonblank character. Take care of very long lines,
// and if there's no blanks/tabs before column
// Essentially a string tokenizer

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]))
    {
        //find cut character
        for(int i = startCol; i <= nextBound; ++i)
        {
            if(isspace(argv[1][i]) && !isspace(argv[1][i-1]))
                currentCut = i - 1;
        }
        //there was no valid "cut" before whitespace or bound itself is valid
        if(!isspace(argv[1][nextBound]) || currentCut <= startCol)
            currentCut = nextBound;

        //print [startCol, cut]
        int printed = 0;
        for(int i = startCol; i <= currentCut; ++i)
        {
            if(isspace(argv[1][i]) && printed == 0)
                continue;
            ++printed;
            putchar(argv[1][i]);
        }
            
        printf("\n");

        //adjust start column for the next run
        startCol = startCol + COL_BOUND;
        ++numOfCuts;
    }

    //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] != '\0'; ++i)
        ;
    return i;
}