ex43

#include <stdio.h>
#include <stdlib.h>
#define LEN 300
#define STR 120

int main(int argc, char *argv[]) {
  int N=10,num=0,i;
  char str[STR][LEN];
  if(argc==2 && atoi(argv[1])!=0) N=atoi(argv[1]);
  else N=10;
  if (argc==1 || N!=10){
        while(fgets(str[num],LEN,stdin)!=NULL) num++;
     if(N<num){
       printf("Last %d strings:\n",N);
        for(i=num-N;i<num;i++) printf("%s",str[i]);
     }
     else{
       printf("All strings:\n");
       for (i=0;i<num;i++) printf("%s",str[i]);
     }
  }
  if(argc==2 && atoi(argv[1])==0){
    N=10;
     FILE *fp;
     if((fp=fopen(argv[1],"r"))!=NULL){
       while(!feof(fp)){
        fgets(str[num],LEN,fp);
         num++;
       }
     }
     else {
        printf("Failed to open the file\n");
        exit(0);
     }
        if(N<num){
          printf("Last %d strings\n",N);
           for(i=num-N-1;i<num;i++){
            printf("%s",str[i]);
           }
        }
        else{
            printf("All strings\n");
            for(i=0;i<num;i++){
            printf("%s",str[i]);
           }
        }
      fclose(fp);
  }
  if(argc==3){
        N=atoi(argv[1]);
     FILE *fp;
     if((fp=fopen(argv[2],"r"))!=NULL){
       while(!feof(fp)){
        fgets(str[num],LEN,fp);
         num++;
       }
     }
     else {
        printf("Failed to open the file\n");
        exit(0);
     }
        if(N<num){
          printf("Last %d strings\n",N);
           for(i=num-N-1;i<num;i++){
            printf("%s",str[i]);
           }
        }
        else{
            printf("All strings\n");
            for(i=0;i<num;i++){
            printf("%s",str[i]);
           }
        }
      fclose(fp);
  }
}