python如何判定字符串的前几个字符是不是数字 python 如何判断一个字符串是不是数字
python3.2.3\u600e\u4e48\u5224\u65ad\u8f93\u5165\u7684\u5b57\u7b26\u4e32\u662f\u6570\u5b57\u8fd8\u662f\u5b57\u6bcd1\u3001python\u4e2d\u5b57\u7b26\u4e32\u65b9\u6cd5str.isalnum\u7528\u6765\u5224\u65ad\u5b57\u7b26\u4e32\u662f\u5426\u7531\u6570\u5b57\u6216\u5b57\u6bcd\u7ec4\u6210\u3002\u5982\u679c\u5b57\u7b26\u4e32\u7531\u7eaf\u6570\u5b57\u7ec4\u6210\uff0c\u8fd4\u56de\u7ed3\u679cTrue\u3002
2\u3001\u5982\u679c\u5b57\u7b26\u4e32\u7531\u7eaf\u5b57\u6bcd\u7ec4\u6210\uff0c\u8fd4\u56de\u7ed3\u679cTrue\u3002
3\u3001\u5982\u679c\u5b57\u7b26\u4e32\u7531\u5b57\u6bcd+\u6570\u5b57\u7ec4\u6210\uff0c\u8fd4\u56de\u7ed3\u679cTrue\u3002\uff08\u4e0d\u533a\u5206\u5b57\u6bcd\u5927\u5c0f\u5199\uff09
4\u3001\u5982\u679c\u5b57\u7b26\u4e32\u9664\u4e86\u5b57\u6bcd\u8ddf\u6570\u5b57\u5916\uff0c\u542b\u6709\u522b\u7684\u5b57\u7b26\uff0c\u8fd4\u56de\u7ed3\u679cFalse\u3002
\u5982\u679c\u8fd9\u4e2a\u5b57\u7b26\u4e32\u662f str, \u5219\u53ef\u4ee5\u7528 str[0].islower() \u6765\u5224\u65ad\u3002
str="123abcd"str[:3].isdigit()
判断字符串前面3个字符是不是数字
先用[:位置值]切片，然后用isdigit判断是否数字
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