C++ strtoul()用法及代碼示例

C /C++中的strtoul()函數根據給定的基數將str中字符串的初始部分轉換為無符號的long int值，該值必須在2到36之間(包括2和36)，或者是特殊值0。此函數將丟棄所有白色空格字符，直到找到第一個非空格字符，然後再使用盡可能多的字符來形成有效的base-n無符號整數表示形式並將其轉換為整數值。

用法:

unsigned long int strtoul(const char *str, char **end, int base)

參數：該函數接受三個強製性參數，如下所述：

str: 指向要解釋的以空終止的字節字符串的指針
end :指向字符的指針(指向char *類型的對象)
base :解釋後的整數值的基數

返回值：該函數返回兩個值，如下所示：

成功時，它將返回一個與str內容相對應的整數值。
如果沒有完成有效的轉換，則返回0。

以下示例程序旨在說明上述函數：

示例1:

// C++ program to illustrate the 
// strtoul() function 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // initiaizing the string 
    char str[256] = "90600 Geeks For Geeks"; 
  
    // reference pointer 
    char* end; 
    long result; 
  
    // finding the unsigned long  
    // integer with base 36 
    result = strtoul(str, &end, 36); 
  
    // printing the unsigned number 
    cout << "The unsigned long integer is : "
         << result << endl; 
    cout << "String in str is : " << end; 
  
    return 0; 
}

輸出：

The unsigned long integer is : 15124320
String in str is :  Geeks For Geeks

示例2:

// C++ program to illustrate the 
// strtoul() function with  
// different bases 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // initiaizing the string 
    char str[256] = "12345 GFG"; 
  
    // reference pointer 
    char* end; 
    long result; 
  
    // finding the unsigned long interger 
    // with base 36 
    result = strtoul(str, &end, 0); 
    cout << "The unsigned long integer is : "
         << result << endl; 
    cout << "String in str is : " << end << endl; 
  
    // finding the unsigned long interger 
    // with base 12 
    result = strtoul(str, &end, 12); 
    cout << "The unsigned long integer is : "
         << result << endl; 
    cout << "String in str is : " << end << endl; 
  
    // finding the unsigned long interger 
    // with base 30 
    result = strtoul(str, &end, 30); 
    cout << "The unsigned long integer is : " 
         << result << endl; 
    cout << "String in str is : " << end << endl; 
  
    return 0; 
}

輸出：

The unsigned long integer is : 12345
String in str is :  GFG
The unsigned long integer is : 24677
String in str is :  GFG
The unsigned long integer is : 866825
String in str is :  GFG

相關用法

注：本文由純淨天空篩選整理自AmanSrivastava1大神的英文原創作品 strtoul() function in C/C++。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。