ZF标示位的问题

[badboy111111]

lea si,adr1
lea di,adr2
cld
don1:lodsb
cmp al,'A'
jb don2
cmp al,'Z'
ja don2
add al,20h
don2:stosb
and al,al
jnz don1

这段代码中ZF是被什么影响的？何时为1的？即jnz don1何时不成立的？

[nineforever]

"and al,al"，ZF取决于al的值

[badboy111111]

噢，那如果是这样，此段程序为何会提早结束，且结果完全不正确
#include<stdio.h>
void lower(char *adr2,char *adr1);
void main()
{
char str[]="C Program AND Assembler Program";
char chr[50];
chr[49]='\0';
lower(chr,str);
printf("Lower String:\n%s\n",chr);
}
void lower(char *adr2,char *adr1)
{
_asm{
lea esi,adr1
lea edi,adr2
cld
don1:lodsb
cmp al,'A'
jb don2
cmp al,'Z'
ja don2
add al,20h
don2:stosb
and al,al
jnz don1
}
}

[cnzdgs]

把两条lea都改成mov。

[badboy111111]

谢了，两位~~今我茅塞顿开：）谢了