Question

我理解如何使用LINQ，因此语法在这里并不重要。 LINQ如何穿插＆＃34;包含＆＃34;以及背景中发生了什么？我知道它找到了所有具有你正在寻找的单词的元素，但它会找到一个包含多个单词的结果吗？例如，我在数据库中有一行名称，如果我使用包含，我将能够找到我的人

Contains("James Bar")

如果真名是James foo Bar

或者查询只是查找

where name like '%James bar%'

并且不返回结果

Answer 1

Here we go --- check it out via reference source: Contains calls IndexOf with a greater equal comparison and that calls an overloaded IndexOf method. hth

        [Pure]
        public bool Contains( string value ) {
             return ( IndexOf(value, StringComparison.Ordinal) >=0 );
        }

        [Pure]
        public int IndexOf(String value, StringComparison comparisonType) {
            return IndexOf(value, 0, this.Length, comparisonType);
        }

        [Pure]
        [System.Security.SecuritySafeCritical]
        public int IndexOf(String value, int startIndex, int count, StringComparison comparisonType) {
            // Validate inputs
            if (value == null)
                throw new ArgumentNullException("value");

            if (startIndex < 0 || startIndex > this.Length)
                throw new ArgumentOutOfRangeException("startIndex", Environment.GetResourceString("ArgumentOutOfRange_Index"));

            if (count < 0 || startIndex > this.Length - count)
                throw new ArgumentOutOfRangeException("count", Environment.GetResourceString("ArgumentOutOfRange_Count"));
            Contract.EndContractBlock();

            switch (comparisonType) {
                case StringComparison.CurrentCulture:
                    return CultureInfo.CurrentCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.None);

                case StringComparison.CurrentCultureIgnoreCase:
                    return CultureInfo.CurrentCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.IgnoreCase);

                case StringComparison.InvariantCulture:
                    return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.None);

                case StringComparison.InvariantCultureIgnoreCase:
                    return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.IgnoreCase);

                case StringComparison.Ordinal:
                    return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.Ordinal);

                case StringComparison.OrdinalIgnoreCase:
                    if (value.IsAscii() && this.IsAscii())
                        return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.IgnoreCase);
                    else
                        return TextInfo.IndexOfStringOrdinalIgnoreCase(this, value, startIndex, count);

                default:
                    throw new ArgumentException(Environment.GetResourceString("NotSupported_StringComparison"), "comparisonType");
            }  
        }

LINQ如何包含工作

1 个答案: