計算一個對象中所有字符串屬性的總長度

Question

我有一個具有100個屬性的對象。 它們都是字符串。我如何計算所有屬性的總長度？

MyAttempt：

public static int GetPropertiesMaxLength(object obj) 
    { 
     int totalMaxLength=0; 
     Type type = obj.GetType(); 
     PropertyInfo[] info = type.GetProperties(); 
     foreach (PropertyInfo property in info) 
     { 
      // ? 
      totalMaxLength+=?? 
     } 
     return totalMaxLength; 
    } 

建議？

Answer 1

爲了獲得給定一個屬性的值的PropertyInfo使用GetValue方法傳遞包含的對象，沒有參數（除非這是一個索引屬性 - 這將使事情變得更加複雜）：

public static int GetPropertiesMaxLength(object obj) { 
    int totalMaxLength=0; 
    Type type = obj.GetType(); 
    PropertyInfo[] info = type.GetProperties(); 
    foreach (PropertyInfo property in info) { 
    if (property.PropertyType == typeof(string)) { 
     string value = property.GetValue(obj, null) as string; 
     totalMaxLength += value.Length; 
    } 
    } 
    return totalMaxLength; 
} 

Answer 2

像這樣

public static int GetPropertiesMaxLength(object obj) 
{ 
    int totalMaxLength=0; 
    Type type = obj.GetType(); 
    PropertyInfo[] info = type.GetProperties(); 
    foreach (PropertyInfo property in info) 
    { 
     totalMaxLength+= property.GetValue(obj, null).ToString().Length; 
    } 
    return totalMaxLength; 
} 

Answer 3

假設所有屬性都是公開：

Object objValue = property.GetValue(obj, null); 
if(objValue != null) 
    totalMaxLength += obj 
Value.ToString().Length; 

如果屬性不是所有公衆，那麼你就必須需要的綁定標誌相結合這樣

Object objValue = property.GetValue(obj, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static /* etc... */, null, null, null); 

Answer 4

使用LINQ Sum()和Where()方法：

public static int GetTotalLengthOfStringProperties(object obj) 
{    
    Type type = obj.GetType(); 
    IEnumerable<PropertyInfo> info = type.GetProperties(); 

    int total = info.Where(p => p.PropertyType == typeof (String)) 
        .Sum(pr => (((String) pr.GetValue(obj, null)) 
           ?? String.Empty).Length); 
    return total; 
} 

PS：爲了使 LINQ你已經添加using System.Linq;

編輯：更通用的方法

/// <summary> 
/// Gets a total length of all string-type properties 
/// </summary> 
/// <param name="obj">The given object</param> 
/// <param name="anyAccessModifier"> 
/// A value which indicating whether non-public and static properties 
/// should be counted 
/// </param> 
/// <returns>A total length of all string-type properties</returns> 
public static int GetTotalLengthOfStringProperties(
            object obj, 
            bool anyAccessModifier) 
{ 
    Func<PropertyInfo, Object, int> resolveLength = (p, o) =>   
     ((((String) p.GetValue(o, null))) ?? String.Empty).Length; 

    Type type = obj.GetType(); 
    IEnumerable<PropertyInfo> info = anyAccessModifier 
     ? type.GetProperties(BindingFlags.NonPublic | BindingFlags.Public | 
          BindingFlags.Instance | BindingFlags.Static) 
     : type.GetProperties();  

    int total = info.Where(p => p.PropertyType == typeof (String)) 
        .Sum(pr => resolveLength(pr, obj)); 
    return total; 
} 

Answer 5

這裏是我的建議：

public static int GetPropertiesMaxLength(object obj) 
    { 
     int totalMaxLength = 0; 
     Type type = obj.GetType(); 
     PropertyInfo[] info = type.GetProperties(); 
     foreach (PropertyInfo property in info) 
     { 
      var value = property.GetValue(obj, null) as string; 
      if (!string.IsNullOrEmpty(value)) 
      { 
       totalMaxLength += value.Length; 
      } 
     } 
     return totalMaxLength; 
    } 

Answer 6

 int count = value.GetType() 
      .GetProperties() 
      .Where(p => p.PropertyType == typeof (string) && p.CanRead) 
      .Select(p => (string) p.GetValue(value, null)) 
      .Sum(s => (string.IsNullOrEmpty(s) ? 0 : s.Length)); 

您可以根據需要修改where子句。例如，如果你想排除靜態或私人等

Answer 7

public static int GetPropertiesMaxLength(object obj) 
{ 
    Type type = obj.GetType(); 
    PropertyInfo[] info = type.GetProperties(); 
    int totalMaxLength = info.Sum(prop => (prop.GetValue(prop, null) as string).Length);   
    return totalMaxLength; 
} 

試試這個。