麻煩與OCaml的嵌套如果

Question

用我的原代碼，我一直就行let numDigits = numDigits - 1 in

原始越來越Error: Parse error: [expr level ;] expected after "in" (in [expr])：

let rec rev_int num = 
    if num/10 == 0 then 
    num 
    else 
    let temp = num mod 10 in 

    let numDigits = String.length(string_of_int num) - 1 in 

    if num < 0 then 
     let numDigits = numDigits - 1 in 
    else 
     let numDigits = numDigits + 0 in 

    let num = (num - temp)/10 in 
    temp * int_of_float(10.0 ** float_of_int numDigits) + rev_int num 

隨着變化：

if num < 0 then 
    let numDigits = numDigits - 1 in; 
else 
    let numDigits = numDigits + 0 in; 

---

if num < 0 then 
    let numDigits = numDigits - 1 in 
else begin 
    let numDigits = numDigits + 0 in end 

我修改了代碼，現在它的工作原理，但我想知道是否有辦法做到嵌套，如果和更少的冗餘。

修：

let rec rev_int num = 
    if num/10 == 0 then 
    num 
    else 
    let temp = num mod 10 in 

    let numDigits = String.length(string_of_int num) - 1 in 

    if num < 0 then 
     let numDigits = numDigits - 1 in 
     let num = (num - temp)/10 in 
     temp * int_of_float(10.0 ** float_of_int numDigits) + rev_int num 
    else 
     let numDigits = numDigits + 0 in 
     let num = (num - temp)/10 in 
     temp * int_of_float(10.0 ** float_of_int numDigits) + rev_int num 

Answer 1

從

Hunan Rostomyan

let rec rev_int num = 
    if num/10 == 0 then 
    num 
    else 
    let temp = num mod 10 in 

    let numDigits = String.length(string_of_int num) - 1 in 

    let numDigits = numDigits - (if num < 0 then 1 else 0) in 
    let num = (num - temp)/10 in 
    temp * int_of_float(10.0 ** float_of_int numDigits) + rev_int num