为什么 scanf 在提供 double 时返回 0.000000？
我有以下汇编代码（为 Linux 上的 NASM 编写）：
; This code has been generated by the 7Basic
; compiler <http://launchpad.net/7basic>
extern printf
extern scanf
SECTION .data
printf_f: db "%f",10,0
scanf_f: db "%f",0
SECTION .bss
v_0 resb 8
SECTION .text
global main
main:
push ebp
mov ebp,esp
push v_0 ; load the address of the variable
push scanf_f ; push the format string
call scanf ; call scanf()
add esp,8
push dword [v_0+4] ; load the upper-half of the double
push dword [v_0] ; load the bottom-half
push printf_f ; push the format string
call printf ; call printf
add esp,12
mov esp,ebp
pop ebp
mov eax,0
ret
当我汇编并运行该程序时，我得到了预期的提示。但是，无论我输入什么数字，输出始终是 0.000000。
我做错了什么？
I have the following assembly code (written for NASM on Linux):
; This code has been generated by the 7Basic
; compiler <http://launchpad.net/7basic>
extern printf
extern scanf
SECTION .data
printf_f: db "%f",10,0
scanf_f: db "%f",0
SECTION .bss
v_0 resb 8
SECTION .text
global main
main:
push ebp
mov ebp,esp
push v_0 ; load the address of the variable
push scanf_f ; push the format string
call scanf ; call scanf()
add esp,8
push dword [v_0+4] ; load the upper-half of the double
push dword [v_0] ; load the bottom-half
push printf_f ; push the format string
call printf ; call printf
add esp,12
mov esp,ebp
pop ebp
mov eax,0
ret
When I assemble and run the program, I get a prompt as expected. However, no matter what number I enter, the output is always 0.000000.
What am I doing wrong?
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您正在尝试使用“%f”标记扫描浮点数，但提供双精度浮点数。将 float 变量传递给 scanf，然后转换为 double 或将 '%lf' 作为格式字符串传递给 scanf。
You are trying to scan a float with the '%f' token but providing a double. Pass in a float variable to scanf and then convert to a double or pass in '%lf' as the format string to scanf.