我正在做一些事情，我意识到我想要在一个字符串中找到多少个/s，然后我突然想到，有几种方法可以做到这一点，但不能决定哪种是最好的(或最简单的)。
目前我想说的是:
string source = "/once/upon/a/time/";
int count = source.Length - source.Replace("/", "").Length;
但我一点都不喜欢，有人愿意吗?
我并不想为此挖掘出正则表达式，对吧?
我知道我的字符串将包含我要搜索的项，所以你可以假设…
当然对于长度为> 1的字符串，
string haystack = "/once/upon/a/time";
string needle = "/";
int needleCount = ( haystack.Length - haystack.Replace(needle,"").Length ) / needle.Length;
当前回答
var conditionalStatement = conditionSetting.Value;
//order of replace matters, remove == before =, incase of ===
conditionalStatement = conditionalStatement.Replace("==", "~").Replace("!=", "~").Replace('=', '~').Replace('!', '~').Replace('>', '~').Replace('<', '~').Replace(">=", "~").Replace("<=", "~");
var listOfValidConditions = new List<string>() { "!=", "==", ">", "<", ">=", "<=" };
if (conditionalStatement.Count(x => x == '~') != 1)
{
result.InvalidFieldList.Add(new KeyFieldData(batch.DECurrentField, "The IsDoubleKeyCondition does not contain a supported conditional statement. Contact System Administrator."));
result.Status = ValidatorStatus.Fail;
return result;
}
需要做一些类似于从字符串测试条件语句的事情。
用单个字符替换我正在寻找的内容，并计算单个字符的实例数。
显然，在发生这种情况之前，您需要检查您正在使用的单个字符是否存在于字符串中，以避免错误计数。
其他回答
string Name = "Very good nice one is very good but is very good nice one this is called the term";
bool valid=true;
int count = 0;
int k=0;
int m = 0;
while (valid)
{
k = Name.Substring(m,Name.Length-m).IndexOf("good");
if (k != -1)
{
count++;
m = m + k + 4;
}
else
valid = false;
}
Console.WriteLine(count + " Times accures");
string source = "/once/upon/a/time/";
int count = 0, n = 0;
while ((n = source.IndexOf('/', n) + 1) != 0) count++;
这是Richard Watson的答案的一个变体，char在字符串中出现的次数越多，效率就会提高一点，代码也会更少!
虽然我必须说，在没有广泛测试每个场景的情况下，我确实看到了使用以下方法的显著速度提升:
int count = 0;
for (int n = 0; n < source.Length; n++) if (source[n] == '/') count++;
string s = "65 fght 6565 4665 hjk";
int count = 0;
foreach (Match m in Regex.Matches(s, "65"))
count++;
public static int GetNumSubstringOccurrences(string text, string search)
{
int num = 0;
int pos = 0;
if (!string.IsNullOrEmpty(text) && !string.IsNullOrEmpty(search))
{
while ((pos = text.IndexOf(search, pos)) > -1)
{
num ++;
pos += search.Length;
}
}
return num;
}
Regex.Matches(input, Regex.Escape("stringToMatch")).Count
