maxstring.c

/* analyses the file and prints the longest string */

 /* pointer arithmetics:
  *
  * push(pointer, v) INDICATES *(pointer++) = v
  * pop(pointer) INDICATES *(--pointer)
  * (*++v)[0] INDICATES (**++v)
  *           INDICATES first char in v
  *           INDICATES name of string/vector v
  * likewise, *v[0] INDICATES **v
  *       and *v[n] INDICATES **(v + n)
  * returntype (*funct)(args) INDICATES a function funct with arguments args which returns...
  * char **argv INDICATES pointer to char pointer
  * int(*v)[len] INDICATES pointer "v" to a vector of "len" int elements
  * int *v[len] INDICATES vector "v" of "len" pointers to int elements
  * void *funct() INDICATES function "funct" that returns a pointer-to-void
  * void (*funct)() INDICATES pointer to a function "funct" that returns void
  *
  */

 /* useful characters: [] # */

 # include <stdio.h>
 # define MAXL 1000 // maximum line length

/* copies the string to another char array */

void copy(char to[], char from[])
    {
    int i = 0;
    for(i = 0; (to[i] = from[i]) != '\0'; i++)
    // stops copying when the source is out of chars
    ;
    }

/* returns the length of a line */

int getlineX(char line[], int limit)
    {
      int c, i;
      for(i = 0; i < limit-1 && (c = getchar()) != EOF && c != '\n'; i++)
      {
        line[i] = c; // the new char is copied
        if(c == '\n') // if end of line, the new char is copied
          {
        line[i] = c;
        ++i;
          }
      }
      line[i] = '\0'; // marks end of line
      return i;
    }

/* main */

int main(int argc, char * argv[])
    {
      int length, max; // length of the current, and maximum, string
      length = max = 0;
      char lines[MAXL]; // input line
      char longest[MAXL]; // longest line

      while((length = getlineX(lines, MAXL)) > 0) // examines all line lengths
      {
       if(length > max)
          {
        max = length;
        copy(longest, lines); // updates longest line
          }
      }

      if(max > 0)
      printf("%s\n", longest); // prints the longest line, if non-null
      return 0;
    }