如何计算特定字符串在另一个字符串中出现的次数。例如,这就是我试图在Javascript中做的事情:
var temp = "This is a string.";
alert(temp.count("is")); //should output '2'
如何计算特定字符串在另一个字符串中出现的次数。例如,这就是我试图在Javascript中做的事情:
var temp = "This is a string.";
alert(temp.count("is")); //should output '2'
当前回答
参数:ustring:超集字符串countChar:子字符串
一个计算JavaScript中子字符串出现次数的函数:
函数subStringCount(ustring,countChar){var correspCount=0;var corresp=false;变量量=0;var prevChar=空;对于(var i=0;i!=ustring.length;i++){如果(ustring.charAt(i)==countChar.charAt(0)&&corresp==false){corresp=真;correspCount+=1;如果(correspCount==countChar.length){数量+=1;corresp=false;correspCount=0;}prevChar=1;}否则如果(ustring.charAt(i)==countChar.charAt(prevChar)&&corresp==true){correspCount+=1;如果(correspCount==countChar.length){数量+=1;corresp=false;correspCount=0;prevChar=空;}其他{prevChar+=1;}}其他{corresp=false;correspCount=0;}} 回报金额;}console.log(subStringCount(“Hello World,Hello World”,“ll”));
其他回答
var countInstances=函数(主体,目标){var全局计数器=0;var concatstring=“”;for(var i=0,j=target.length;i<body.length;i++){concatstring=body.substring(i-1,j);if(concatstring===目标){全局计数器+=1;concatstring='';}}返回全局计数器;};console.log(countInstance('abcabc','abc'));//==>2.console.log(countInstance('ababa','aba'));//==>2.console.log(countInstance('aaabbb','ab'));//==>1.
只需编码打高尔夫球丽贝卡·切尔诺夫的解决方案:-)
alert(("This is a string.".match(/is/g) || []).length);
您可以使用match来定义这样的函数:
String.prototype.count = function(search) {
var m = this.match(new RegExp(search.toString().replace(/(?=[.\\+*?[^\]$(){}\|])/g, "\\"), "g"));
return m ? m.length:0;
}
试试看:
function countString(str, search){
var count=0;
var index=str.indexOf(search);
while(index!=-1){
count++;
index=str.indexOf(search,index+1);
}
return count;
}
第二次迭代次数较少(仅当子字符串的第一个字母匹配时),但循环仍使用2:
function findSubstringOccurrences(str, word) {
let occurrences = 0;
for(let i=0; i<str.length; i++){
if(word[0] === str[i]){ // to make it faster and iterate less
for(let j=0; j<word.length; j++){
if(str[i+j] !== word[j]) break;
if(j === word.length - 1) occurrences++;
}
}
}
return occurrences;
}
console.log(findSubstringOccurrences("jdlfkfomgkdjfomglo", "omg"));