//uplow.c --- @CopyLeft by tsaiwn@csie.nctu.edu.tw
//程式庫中的 isupper(int) 遇到大寫字母不一定回傳 1
//因為它可能把它分類, 回傳的是類別代號; 反正不是 0 就代表 true
// 此例用 Dev-Cpp (MinW32 gcc/g++), isupper 是回傳 1
//  但請注意此例中, 程式庫的 islower 是回傳 0 或 2; 不會是 1
//// 我們自己寫的 myLower 則是回傳 0 或 1; 這是 OK 的!
#include <ctype.h>
#include <stdio.h>
int myUp(int x) {
    return x >= 'A'  && x <= 'Z';  // 'A'..'Z' 才回答 yes
}
int myLower(int x) {
    return x >= 'a'  && x <= 'z';  // 'a'..'z' 才回答 yes
}
int main( ) {
    printf("isupper(65)==%d, isupper(97)==%d\n",
           isupper(65), isupper(97) ); //65=='A', 97=='a'
    if(myUp('a'))printf(" YES a is UPPER; ");
    else printf(" no. a is NOT UPPER case\n");
    printf(" myUp('a')=%d\n", myUp('a') );
///
    if(myUp('A'))printf(" YES A is UPPER; ");
    else printf(" no. A is NOT UPPER case\n");
    printf(" myUp('A')=%d\n", myUp('A') );
/// ///
    printf("islower('A')==%d, islower('a')==%d\n",
           islower('A'), islower('a') ); //65=='A', 97=='a'
    if(myLower('a'))printf(" YES a is lower; ");
    else printf(" no. a is NOT in lower case\n");
    printf(" myLower('a')=%d\n", myLower('a') );
///
    if(myLower('A'))printf(" Yes. A is lower; ");
    else printf(" no. A is NOT in lower case\n");
    printf(" myUp('A')=%d\n", myUp('A') );
///
    printf(" ... Hit ENTER key ...");
    getchar( ); return 0;
}
/******
D:\testc> path c:\Dev-Cpp\bin;%path%
D:\testc> gcc uplow.c
D:\testc> a
isupper(65)==1, isupper(97)==0
 no. a is NOT UPPER case
 myUp('a')=0
 YES A is UPPER;  myUp('A')=1
islower('A')==0, islower('a')==2
 YES a is lower;  myLower('a')=1
 no. A is NOT in lower case
 myUp('A')=1
 ... Hit ENTER key ...
=======================************/