C语言字符串统计：长度、大小写字母和数字字符数量

#include <stdio.h>\n#include <ctype.h>\n\nint main() {\n char str[100];\n int length = 0;\n int uppercase_letters = 0;\n int lowercase_letters = 0;\n int digits = 0;\n \n printf("请输入一个字符串：");\n fgets(str, sizeof(str), stdin);\n \n // 统计实际长度\n while (str[length] != '\0') {\n length++;\n }\n \n // 统计大写字母、小写字母和数字字符的数量\n for (int i = 0; i < length; i++) {\n if (isupper(str[i])) {\n uppercase_letters++;\n } else if (islower(str[i])) {\n lowercase_letters++;\n } else if (isdigit(str[i])) {\n digits++;\n }\n }\n \n printf("实际长度：%d\n", length - 1); // 减去换行符的长度\n printf("大写字母数量：%d\n", uppercase_letters);\n printf("小写字母数量：%d\n", lowercase_letters);\n printf("数字字符数量：%d\n", digits);\n \n return 0;\n}