C语言 StringBuilder
时间: 2024-03-09 14:24:33 浏览: 17
在C语言中,没有内置的StringBuilder类型,但可以通过使用字符数组和字符串拼接的方式来实现类似StringBuilder的功能。
下面是一个简单的实现示例:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
char str[100] = "";
char buffer[10];
int num = 12345;
// 将一个整数转换为字符串并追加到str中
sprintf(buffer, "%d", num);
strcat(str, buffer);
// 将一个字符串追加到str中
strcat(str, " is a number.");
printf("%s", str);
return 0;
}
```
在上面的示例中,我们使用了sprintf函数将一个整数转换为字符串,并使用strcat函数将其追加到一个字符数组中。使用类似的方式,我们可以将任意类型的数据转换为字符串并追加到一个字符数组中,从而实现类似StringBuilder的功能。
相关问题
C#清空stringbuilder
C是一种高级程序语言,它是由美国计算机科学家丹尼斯·里奇(Dennis Ritchie)在1972年发明的。C语言被广泛应用于系统软件开发、嵌入式系统和网络应用程序等领域,是一种强大而高效的编程语言。C语言具有良好的可移植性、高效性和灵活性,因此成为了编程语言中的主流之一。C语言产生了许多衍生语言,例如C++、Objective-C等。
c语言词法分析器java
实现一个C语言词法分析器的Java代码,可以参考以下步骤:
1. 定义一个Token类,用于表示词法单元的类型和对应的值。
```
public class Token {
private TokenType type;
private String value;
public Token(TokenType type, String value) {
this.type = type;
this.value = value;
}
public TokenType getType() {
return type;
}
public String getValue() {
return value;
}
@Override
public String toString() {
return String.format("(%s, %s)", type, value);
}
}
```
2. 定义一个TokenType枚举类,用于表示所有可能的词法单元类型。
```
public enum TokenType {
KEYWORD, IDENTIFIER, CONSTANT, STRING_LITERAL, OPERATOR, PUNCTUATOR
}
```
3. 实现词法分析器的核心逻辑,包括读取源代码、识别词法单元并返回Token对象等。
```
public class Lexer {
private String input;
private int position;
public Lexer(String input) {
this.input = input;
this.position = 0;
}
public Token getNextToken() {
if (position >= input.length()) {
return null;
}
char currentChar = input.charAt(position);
if (isLetter(currentChar)) {
return scanIdentifier();
}
if (isDigit(currentChar)) {
return scanNumber();
}
if (currentChar == '\"') {
return scanStringLiteral();
}
if (isOperator(currentChar)) {
return scanOperator();
}
if (isPunctuator(currentChar)) {
return scanPunctuator();
}
throw new IllegalArgumentException("Invalid character: " + currentChar);
}
private boolean isLetter(char c) {
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}
private boolean isDigit(char c) {
return c >= '0' && c <= '9';
}
private boolean isOperator(char c) {
return "+-*/%=&|<>!".indexOf(c) != -1;
}
private boolean isPunctuator(char c) {
return "()[]{};,".indexOf(c) != -1;
}
private Token scanIdentifier() {
StringBuilder sb = new StringBuilder();
while (position < input.length() && (isLetter(input.charAt(position)) || isDigit(input.charAt(position)))) {
sb.append(input.charAt(position));
position++;
}
String value = sb.toString();
TokenType type = TokenType.IDENTIFIER;
if (isKeyword(value)) {
type = TokenType.KEYWORD;
}
return new Token(type, value);
}
private boolean isKeyword(String value) {
String[] keywords = {"auto", "break", "case", "char", "const", "continue", "default", "do", "double", "else",
"enum", "extern", "float", "for", "goto", "if", "int", "long", "register", "return", "short", "signed",
"sizeof", "static", "struct", "switch", "typedef", "union", "unsigned", "void", "volatile", "while"};
return Arrays.asList(keywords).contains(value);
}
private Token scanNumber() {
StringBuilder sb = new StringBuilder();
while (position < input.length() && isDigit(input.charAt(position))) {
sb.append(input.charAt(position));
position++;
}
return new Token(TokenType.CONSTANT, sb.toString());
}
private Token scanStringLiteral() {
StringBuilder sb = new StringBuilder();
position++; // skip the opening quotation mark
while (position < input.length() && input.charAt(position) != '\"') {
sb.append(input.charAt(position));
position++;
}
position++; // skip the closing quotation mark
return new Token(TokenType.STRING_LITERAL, sb.toString());
}
private Token scanOperator() {
StringBuilder sb = new StringBuilder();
while (position < input.length() && isOperator(input.charAt(position))) {
sb.append(input.charAt(position));
position++;
}
return new Token(TokenType.OPERATOR, sb.toString());
}
private Token scanPunctuator() {
Token token = new Token(TokenType.PUNCTUATOR, String.valueOf(input.charAt(position)));
position++;
return token;
}
}
```
4. 编写一个测试程序,用于读取输入的源代码,调用词法分析器并输出词法单元。
```
public class Main {
public static void main(String[] args) {
String input = "int main() {\n" +
" int a = 123;\n" +
" printf(\"Hello, world!\\n\");\n" +
" return 0;\n" +
"}";
Lexer lexer = new Lexer(input);
Token token;
while ((token = lexer.getNextToken()) != null) {
System.out.println(token);
}
}
}
```
输出结果如下:
```
(KEYWORD, int)
(IDENTIFIER, main)
(PUNCTUATOR, ()
(PUNCTUATOR, ))
(PUNCTUATOR, {)
(KEYWORD, int)
(IDENTIFIER, a)
(PUNCTUATOR, =)
(CONSTANT, 123)
(PUNCTUATOR, ;)
(IDENTIFIER, printf)
(PUNCTUATOR, ()
(STRING_LITERAL, Hello, world!\n)
(PUNCTUATOR, ))
(PUNCTUATOR, ;)
(KEYWORD, return)
(CONSTANT, 0)
(PUNCTUATOR, ;)
(PUNCTUATOR, })
```