A solution for Project Five

/* MCS 275 Project Five: Recording Temperatures */

#include <stdio.h>
#include <string.h>

void logtemp ( FILE *fp );
/* logs temperatures for cities given on input */

int search ( FILE *fp, char *s );
/* return 1 if string found in the file */

int main ( int argc, char *argv[] )
{
   FILE *fp;

   if (argc < 2)
   {
      printf("Need one file as argument.  Please try again...\n");
      exit(1);
   }
   else
   {
      fp = fopen(argv[1],"r");
      if (fp == NULL)
         fp = fopen(argv[1],"w");
      else
      {
         fclose(fp);
         fp = fopen(argv[1],"r+");
      }
      logtemp(fp);
   }
   fclose(fp);
   return 0;
}

int search ( FILE *fp, char *s )
{
   int  i,okay;
   int  len = strlen(s);
   char city[80];
   char c;
   
   for (;;)
   {
      for (i=0; i < len; i++)
      {
         okay = fscanf(fp,"%c", &city[i]);
         if (city[i] == '\n') okay = 0;
         if (okay == 0) break;
      }
      city[len] = '\0';
      if (okay == 1)
         if (strcmp(s,city) == 0)
            return 1;
      fscanf(fp,"%*[^\n]");  /* skip rest of line */
      c = getc(fp);          /* skip new line symbol */
      if (c == EOF) break;
   }

   return 0;
}

void logtemp ( FILE *fp )
{
   char city[80];
   float t;
   int found;
   char c;

   for (;;)
   {
      printf("Give name of city (enter to stop) : ");
      city[0] = '\n';
      scanf("%79[^\n]", city);
      if (city[0] == '\n') break;
      found = search(fp,city);
      if (found == 0)
      {
         fprintf(fp,"%s", city);
         printf("Give temperature in %s : ", city);
         scanf("%f", &t);
         fprintf(fp,"%8.1f\n", t);
      }
      else
      {
         fscanf(fp,"%f", &t);
         printf("The current temperature in %s is %.1f\n", city, t);
         printf("Give the new temperature in %s : ", city);
         scanf("%f", &t);
         fseek(fp,-8,1);
         fprintf(fp,"%8.1f\n",t);
      }
      c = getchar();         /* skip new line symbol */
      rewind(fp);
   }
}