与find()方法不同的是,index()方法在找不到子字符串时会抛出ValueError异常,因此需要进行异常处理。 deffind_all_positions(string,substring):positions=[]start=0try:whileTrue:position=string.index(substring,start)positions.append(position)start=position+1exceptValueError:passreturnpositions string="Hello, Worl...
Note that find() function returns the index position of the substring if it’s found, otherwise it returns -1. Count of Substring Occurrence We can usecount() functionto find the number of occurrences of a substring in the string. s = 'My Name is Pankaj' print('Substring count =', s...
If substring exists inside the string, it returns the lowest index in the string where substring is found. If substring doesn't exist inside the string, it raises aValueErrorexception. Theindex()method is similar to thefind()method for strings. The only difference is thatfind()method returns-...
Theindexmethod in particular, returns the index of the given substring, inside the string.The substring that we pass, can be as long or as short as we want.And what happens if the string doesn’t have the substring we’re looking for?The index method can’t return a number because the...
python 自带的两个查找字符串的方法:find 和rfind. Python String find() Method Description: This method determines ifstroccurs in string, or in a substring of string if starting indexbegand ending indexendare given. beg 和 end 可以缺省,这样find整个字符串 ...
# 从后往前查找字符串deffind_last_occurrence(string,substring):n=len(substring)foriinrange(len(string)-n,-1,-1):ifstring[i:i+n]==substring:returnireturn-1 1. 2. 3. 4. 5. 6. 7. 上述代码中,string是待查找的字符串,substring是待查找的子字符串。通过循环遍历,分别比较从末尾开始的子字符...
find() Return Value Thefind()method returns an integer value: If the substring exists inside the string, it returns the index of the first occurence of the substring. If a substring doesn't exist inside the string, it returns-1. Working of find() method ...
def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ """ S.find(sub[, start[, end]]) -> int Return the lowest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are ...
| Return the lowest indexinS where substring subisfound,| such that subiscontained within s[start:end]. Optional| arguments startandend are interpreted asinslice notation.| | Return -1 on failure 假定S为string类型的对象,调用find函数,将子串或子串的子串(也就是子串从start到end的切片)作为参数传...
print(find_Index("Python Exercises", "yt")) print(find_Index("Python Exercises", "PY")) Sample Output: 7 1 Not found Flowchart: For more Practice: Solve these Related Problems: Write a Python program to find the starting index of a given substring in a string and return "Not found" ...