文字列の長さを調べる

C Delphi

明解Ｃ言語 入門編 > 11. 文字列とポインタ >

文字列の長さを調べる

C



#include <stdio.h>

#include <string.h>
unsigned str_length(const char* str)

{

    size_t len = 0;
    while (*str++)

        len++;
    return len;

}
int main(int argc, char* argv[])

{

    char str[100] = "ABC";
    printf("sizeof(\"%s\") = %u\n", str, (unsigned)sizeof(str));

    printf("strlen(\"%s\") = %u\n", str, strlen(str));

    printf("str_length(\"%s\") = %u\n", str, str_length(str));
    return 0;

}

実行結果



R:\>lesson084\project1.exe

sizeof("ABC") = 100

strlen("ABC") = 3

str_length("ABC") = 3

Delphi



program Project1;
{$APPTYPE CONSOLE}
uses

    SysUtils;
function str_length(str:PChar):Integer;

begin

    result := 0;

    while (str^ <> #0) do

    begin

        Inc(str);

        Inc(result);

    end;

end;
procedure main();

const

    str: String                = 'ABC';

    ptr: array[0..255] of Char = '12345';

begin

    Writeln(Format('length(''%s'')       = %d', [str, Length(str)]));

    Writeln(Format('sizeof(''%s'')     = %d', [ptr, SizeOf(ptr)]));

    Writeln(Format('strlen(''%s'')     = %d', [ptr, StrLen(ptr)]));

    Writeln(Format('str_length(''%s'') = %d', [ptr, str_length(ptr)]));

end;
begin

    main;

end.

実行結果



S:\>lesson084\project1.exe

length('ABC')       = 3

sizeof('12345')     = 256

strlen('12345')     = 5

str_length('12345') = 5