關於C的整數促進，簡稱

Question

void main(){
    char c;
    unsigned char uc;
    unsigned short us1, us2;
    short s1, s2;

    c = 0xf0; uc = 0xf0;
    us1 = c; us2 = uc;
    printf("us1 = %x, \t us2 = %x\n", us1, us2);
    s1 = c; s2 = uc;
    printf("s1 = %x, \t s2 = %x\n", s1, s2);
}

結果：us1 = fff0，us2 = f0 s1 = fffffff0，s2 = f0

為什么s1是這樣的？ 即使在32位且short的大小為2個字節

Answer 1

這是因為在對printf()的變量參數調用中， short被提升為int 。