是否有 scanf 的格式化程序允许我忽略空格直到下一个字符串，我需要读取空格？ C 语言

Question

Doing a poject for uni,

Facing a problem where I need to read a line where I need to read the first char to choose the command (used a getchar, works fine). The first char is separated by an undetermined amount of ' ' until a string is input. The string itself needs to be able to read until the end of the line (including ' ' ).

Would this work?

char c;
c= getchar();
while(c==' ')
  c=getchar();

or would the last c get "eaten"? then I would need to add it manually to the string, right?

As a follow up, if I did after:

string[0]=c;
scanf("%20[^\n]", string);

would I overwrite the first character?

Answer 1

Yes,

string[0]=c;
scanf("%20[^\n]", string);

will overwrite the first character.

You can add a whitespace character to the format specifier to tell scanf() ignore whitespace characters.

scanf(" %20[^\n]", string);

If you want to skip whitespace characters manually, you can use ungetc() to put the first wanted character back to the stream

ungetc(c, stdin);
scanf("%20[^\n]", string);

or manually put the character to the array, then have scanf() store what is read after the first element.

string[0]=c;
scanf("%20[^\n]", string + 1);