2. 获取字符串第一个字符 FirstChar exporttypeFirstChar<T> = Textends`${infer L}${infer R}`? L :never;typeA =FirstChar<"BFE">;// 'B'typeB =FirstChar<"Echoyya">;// 'd'typeC =FirstChar<"">;// never 3. 获取字符串最后一个字符 LastChar exporttypeLastChar<T, Fextendsstring="...
U : never;//示例type result0 = InferArray<[number,string]>;//string | numbertype result1 = InferArray<string[]>;//stringtype result2 = InferArray<number[]>;//number 🐹 推断数组(或者元组)第一个元素的类型 定义: type InferFirst<T extends unknown[]> = T extends [infer P, ...infer...
R : never type A = FirstChar<'BFE'> // 'B' type B = FirstChar<'dev'> // 'd' type C = FirstChar<''> // never 1. 2. 3. 4. LastChar获取字符串字面量中的最后一个字符 type LastChar<T extends string, A extends string[] = []> = T extends `${infer P}${infer Q}` ?
return false } const deque = new Deque() const lowerString = aString.toLowerCase().split(' ').join('') // 加入队列 for (let i = 0; i < lowerString.length; i++) { deque.addBack(lowerString[i]) } let isEqual = true let firstChar = '' let lastChar = '' while (deque.siz...
if (typeof idOrName === 'string') { // 如果 idOrName 是字符串,则按名称搜索 console.log('Searching by name:', idOrName); return this.items.find(user => user.name === idOrName); } else if (typeof idOrName === 'number') { ...
functionthrowError(){thrownewError();}functionfirstChar(msg:string|undefined){if(msg===undefined)throwError();letchr=msg.charAt(1)// Object is possibly 'undefined'.} 由于编译器不知道 throwError 是一个无返回的函数,所以throwError()之后的代码被认为在任意情况下都是可达的,让编译器误会 msg 的类...
/** * @file 找出字符串中第一个只出现一次的字符 */ function firstSingleChar(str: string) ...
let text = 'TypeScript'; // Get string length let length: number = text.length; // 10 // Access individual characters let firstChar: string = text[0]; // 'T' let lastChar: string = text[text.length - 1]; // 't' Code language: JavaScript (javascript) String Methods Searching an...
由于编译器不知道 throwError 是一个无返回的函数,所以throwError()之后的代码被认为在任意情况下都是可达的,让编译器误会 msg 的类型是 string | undefined。 这时候如果标记上了 never 类型,那么 msg 的类型将会在空检查之后收窄为 string: functionthrowError():never{thrownewError();}functionfirstChar(msg:...
int countOccurrencesOfCharacter(char *string, char character) {int count = 0;for (int i = 0;string[i] != '\0'; i++) {if (string[i] ==character) {count++;}}return count;} 那么可像下面这样从C#中调用: using System;using System.Runtime.InteropServices; ...