Python |查找给定字符串中字符的位置
给定一个字符串和一个字符，您的任务是找到该字符在字符串中的第一个位置。这些类型的问题是非常有竞争力的编程，您需要定位字符串中字符的位置。 我们来讨论几个解决问题的方法。 方法#1:使用天真方法
Python 3
# Python3 code to demonstrate
# to find the first position of the character
# in a given string
# Initializing string
ini_string = 'abcdef'
# Character to find
c = "b"
# printing initial string and character
print ("initial_string : ", ini_string, "\ncharacter_to_find : ", c)
# Using Naive Method
res = None
for i in range(0, len(ini_string)):
if ini_string[i] == c:
res = i + 1
break
if res == None:
print ("No such character available in string")
else:
print ("Character {} is present at {}".format(c, str(res)))
Output:
initial_string : abcdef
character_to_find : b
Character b is present at 2
方法 2:使用查找 如果字符不存在，该方法返回-1。
Python 3
# Python3 code to demonstrate
# to find first position of character
# in a given string
# Initializing string
ini_string = 'abcdef'
ini_string2 = 'xyze'
# Character to find
c = "b"
# printing initial string and character
print ("initial_strings : ", ini_string, " ",
ini_string2, "\ncharacter_to_find : ", c)
# Using find Method
res1 = ini_string.find(c)
res2 = ini_string2.find(c)
if res1 == -1:
print ("No such character available in string {}".format(
ini_string))
else:
print ("Character {} in string {} is present at {}".format(
c, ini_string, str(res1 + 1)))
if res2 == -1:
print ("No such character available in string {}".format(
ini_string2))
else:
print ("Character {} in string {} is present at {}".format(
c, ini_string2, str(res2 + 1)))
输出:
initial_strings : abcdef xyze
character_to_find : b
Character b in string abcdef is present at 2
No such character available in string xyze
方法#3:使用索引() 如果字符不存在 该方法会引发值错误
Python 3
# Python3 code to demonstrate
# to find first position of character
# in a given string
# Initializing string
ini_string1 = 'xyze'
# Character to find
c = "b"
# printing initial string and character
print ("initial_strings : ", ini_string1,
"\ncharacter_to_find : ", c)
# Using index Method
try:
res = ini_string1.index(c)
print ("Character {} in string {} is present at {}".format(
c, ini_string1, str(res + 1)))
except ValueError as e:
print ("No such character available in string {}".format(ini_string1))
输出:
initial_strings : xyze
character_to_find : b
No such character available in string xyze
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