How to read empty string in C -

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i have problem reading empty string in c. want read string following -

  1. ass
  2. ball
  3. (empty)
  4. cat

but when use gets() not treat (empty) string[2]. reads 'cat' string[2]. how can solve problem?

char str1[15002][12]; char str2[15002][12]; char s[25]; map<string,int> map;  int main() {     int ncase, i, j, n1, n2, count, case;      freopen("input.txt","r",stdin);     freopen("output.txt","w",stdout);      scanf("%d",&ncase);      case = 1;     while(ncase > 0)     {         map.clear();          //this necessery part         scanf("%d %d\n",&n1,&n2);         count = 0;          printf("n1=%d n2=%d\n",n1,n2);         for(i = 0; < n1; i++)         {           gets(str1[i]);         }          for(i = 0; < n2; i++)         {             gets(str2[i]);         }          //end of reading input          for(i = 0; < n1; i++)         {             for(j = 0; j < n2; j++)             {                 strcpy(s,str1[i]);                 strcat(s,str2[j]);                  if(map[s] == 0){                     count += 1;                     map[s] = 1;                 }             }         }          printf("case %d: %d\n", case, count);         case++;         ncase--;     }     return 0; }

and input can like

i have given code here. input may like

line1>1 line2>3 3 line3>(empty line) line4>a line5>b line6>c line7>(empty) line8>b

and expect

str1[0]=(empty). str1[1]=a; str1[2]=b;

and

str2[0]=c; str2[1]=(empty); str2[2]=b;




ok, @ last found problem. line 

printf("n1=%d n2=%d\n",n1,n2);

which creates problem in taking input gets(). instead of taking newline integer n1, n2, take newline ("%c",&ch) , okay.

thanks answered me.

chances are, string contains \r\n\0 (or \n\r\0 - never remember comes first). \r\n newline on windows , \0 terminating character of string.

in general, if first character of string \r or\n, read empty string. fwiw should work on platforms:

char* string; // initialize string , read if (strlen(string) == 0 || string[0] == `\r` || string[0] == `\n`)   // string empty

update: mention use gets, , read file. however, latter need fgets, there confusion here. note fgets includes trailing newline character in string returned, while gets not.

update3: way read file indeed fishy. reopen standard input read file - why??? standard practice fopen file, read fscanf , fgets.

update2: stupid (and clever @salil :-). say

it read 'cat' string[3]

since c arrays indexed 0, string[3] contains 4th line read! third line stored in string[2] - bet contain empty string looking for.


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