Slauncha

#include<stdio.h>

#define MAXSIZE 100 /*max size line */
#define END '!'

int readLine(char s[], int lim);
void copyLine(char dest[], char src[]);

/*
 read the input char and save the char into s
 return : s[] size */

int readLine(char s[], int lim)
{
    int c; /* char read */
    int i;
    for (i=0; i<lim-1 && ((c=getchar())!=END) && c != '\n';
            ++i) {
        s[i] = c;
    }
    if (c=='\n') {
        s[i] = c;
        ++i;
    }
    s[i] = '\0';    /* to finalize the line */
    return i;
}

/*
copy src to dest
*/

void copyLine(char dest[], char src[])
{
    int i=0;
    while ((dest[i] = src[i]) != '\0') {
        ++i;
    }
}


int main(int argc, char** argv)
{
    int l;
    int max; /* size of the longest line current read */
    char line[MAXSIZE];
    char longestLine[MAXSIZE];

    max = 0;
    while ((l = readLine(line, MAXSIZE)) > 0) {
        if (l > max) {
            max = l;
            copyLine(longestLine, line);
        }
    }


    if (max > 0)
        printf("Longest line is : %s", longestLine);

return 0;

}

  copy.c

  Pour finir la saisie, sur une ligne vierge, saisir le caractère "!", paramétrable en changeant la valeur de END en define.

  Exécution

$gcc copy.c -o copy
$chmod +x copy
$./copy
azerty
azertyuiop
azer
!
Longest line is : azertyuiop
$