引言
C语言，作为一种历史悠久且功能强大的编程语言，至今仍广泛应用于系统软件、嵌入式系统、操作系统等领域。对于初学者来说，C语言的学习之路充满了挑战和乐趣。本文将带你从C语言的基础语法开始，逐步深入到实战应用，通过30个经典实例的解析和技巧分享，帮助你更好地掌握C语言编程。
第一章：C语言基础入门
1.1 C语言发展历程
C语言由Dennis Ritchie于1972年发明，最初用于开发Unix操作系统。此后，C语言凭借其简洁、高效、可移植等优点，迅速成为最受欢迎的编程语言之一。
1.2 C语言基础语法
本章节将介绍C语言的基础语法，包括数据类型、变量、运算符、控制语句等。
数据类型
- int：整数类型
- float：浮点数类型
- double：双精度浮点数类型
- char：字符类型
变量
变量是存储数据的容器，具有名称和数据类型。
int a = 10;
float b = 3.14;
char c = 'A';
运算符
C语言提供了丰富的运算符，包括算术运算符、关系运算符、逻辑运算符等。
int a = 5, b = 3;
int sum = a + b; // 算术运算符
int is_equal = a == b; // 关系运算符
int is_greater = a > b; // 关系运算符
int is_true = 1 && 1; // 逻辑运算符
控制语句
C语言提供了多种控制语句，用于控制程序的执行流程。
if (a > b) {
// 条件判断语句
}
for (int i = 0; i < 10; i++) {
// 循环语句
}
while (1) {
// 无限循环语句
}
第二章：30个经典实例解析
2.1 实例1：计算阶乘
#include <stdio.h>
int factorial(int n) {
if (n == 0)
return 1;
return n * factorial(n - 1);
}
int main() {
int n = 5;
printf("Factorial of %d is %d\n", n, factorial(n));
return 0;
}
2.2 实例2：判断素数
#include <stdio.h>
#include <stdbool.h>
bool is_prime(int n) {
if (n <= 1)
return false;
for (int i = 2; i * i <= n; i++) {
if (n % i == 0)
return false;
}
return true;
}
int main() {
int n = 17;
if (is_prime(n))
printf("%d is a prime number\n", n);
else
printf("%d is not a prime number\n", n);
return 0;
}
2.3 实例3：字符串逆序
#include <stdio.h>
#include <string.h>
void reverse_string(char *str) {
int len = strlen(str);
for (int i = 0; i < len / 2; i++) {
char temp = str[i];
str[i] = str[len - i - 1];
str[len - i - 1] = temp;
}
}
int main() {
char str[] = "Hello, World!";
printf("Original string: %s\n", str);
reverse_string(str);
printf("Reversed string: %s\n", str);
return 0;
}
2.4 实例4：冒泡排序
#include <stdio.h>
void bubble_sort(int arr[], int n) {
for (int i = 0; i < n - 1; i++) {
for (int j = 0; j < n - i - 1; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
}
int main() {
int arr[] = {64, 34, 25, 12, 22, 11, 90};
int n = sizeof(arr) / sizeof(arr[0]);
bubble_sort(arr, n);
printf("Sorted array: \n");
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("\n");
return 0;
}
2.5 实例5：快速排序
#include <stdio.h>
int partition(int arr[], int low, int high) {
int pivot = arr[high];
int i = (low - 1);
for (int j = low; j <= high - 1; j++) {
if (arr[j] < pivot) {
i++;
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
int temp = arr[i + 1];
arr[i + 1] = arr[high];
arr[high] = temp;
return (i + 1);
}
void quick_sort(int arr[], int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quick_sort(arr, low, pi - 1);
quick_sort(arr, pi + 1, high);
}
}
int main() {
int arr[] = {10, 7, 8, 9, 1, 5};
int n = sizeof(arr) / sizeof(arr[0]);
quick_sort(arr, 0, n - 1);
printf("Sorted array: \n");
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("\n");
return 0;
}
2.6 实例6：二分查找
#include <stdio.h>
int binary_search(int arr[], int low, int high, int x) {
if (high >= low) {
int mid = low + (high - low) / 2;
if (arr[mid] == x)
return mid;
if (arr[mid] > x)
return binary_search(arr, low, mid - 1, x);
return binary_search(arr, mid + 1, high, x);
}
return -1;
}
int main() {
int arr[] = {2, 3, 4, 10, 40};
int n = sizeof(arr) / sizeof(arr[0]);
int x = 10;
int result = binary_search(arr, 0, n - 1, x);
if (result == -1)
printf("Element is not present in array");
else
printf("Element is present at index %d", result);
return 0;
}
2.7 实例7：合并两个有序数组
#include <stdio.h>
void merge(int arr[], int n1, int n2) {
int i = 0, j = 0, k = 0;
int merged[n1 + n2];
while (i < n1 && j < n2) {
if (arr[i] <= arr[j]) {
merged[k] = arr[i];
i++;
} else {
merged[k] = arr[j];
j++;
}
k++;
}
while (i < n1) {
merged[k] = arr[i];
i++;
k++;
}
while (j < n2) {
merged[k] = arr[j];
j++;
k++;
}
for (i = 0; i < n1 + n2; i++)
arr[i] = merged[i];
}
int main() {
int arr1[] = {1, 3, 5, 7};
int arr2[] = {2, 4, 6, 8};
int n1 = sizeof(arr1) / sizeof(arr1[0]);
int n2 = sizeof(arr2) / sizeof(arr2[0]);
merge(arr1, n1, n2);
printf("Merged array: \n");
for (int i = 0; i < n1 + n2; i++)
printf("%d ", arr1[i]);
printf("\n");
return 0;
}
2.8 实例9：字符串查找
#include <stdio.h>
#include <string.h>
int find_substring(char *str, char *substr) {
return strstr(str, substr) - str;
}
int main() {
char str[] = "Hello, World!";
char substr[] = "World";
int result = find_substring(str, substr);
if (result == -1)
printf("Substring not found in string");
else
printf("Substring found at index %d", result);
return 0;
}
2.9 实例10：计算字符串长度
#include <stdio.h>
#include <string.h>
int string_length(char *str) {
return strlen(str);
}
int main() {
char str[] = "Hello, World!";
int len = string_length(str);
printf("Length of string: %d\n", len);
return 0;
}
2.10 实例11：字符串复制
#include <stdio.h>
#include <string.h>
void string_copy(char *dest, char *src) {
strcpy(dest, src);
}
int main() {
char src[] = "Hello, World!";
char dest[100];
string_copy(dest, src);
printf("Copied string: %s\n", dest);
return 0;
}
2.11 实例12：字符串连接
#include <stdio.h>
#include <string.h>
void string_concat(char *dest, char *src) {
strcat(dest, src);
}
int main() {
char str1[] = "Hello, ";
char str2[] = "World!";
char result[100];
string_concat(result, str1);
string_concat(result, str2);
printf("Concatenated string: %s\n", result);
return 0;
}
2.12 实例13：字符串比较
#include <stdio.h>
#include <string.h>
int string_compare(char *str1, char *str2) {
return strcmp(str1, str2);
}
int main() {
char str1[] = "Hello";
char str2[] = "World";
int result = string_compare(str1, str2);
if (result == 0)
printf("Strings are equal");
else if (result > 0)
printf("Str1 is greater than Str2");
else
printf("Str1 is less than Str2");
return 0;
}
2.13 实例14：字符串转换为大写
#include <stdio.h>
#include <ctype.h>
void string_to_upper(char *str) {
for (int i = 0; str[i] != '\0'; i++) {
str[i] = toupper(str[i]);
}
}
int main() {
char str[] = "Hello, World!";
string_to_upper(str);
printf("Uppercase string: %s\n", str);
return 0;
}
2.14 实例15：字符串转换为小写
#include <stdio.h>
#include <ctype.h>
void string_to_lower(char *str) {
for (int i = 0; str[i] != '\0'; i++) {
str[i] = tolower(str[i]);
}
}
int main() {
char str[] = "Hello, World!";
string_to_lower(str);
printf("Lowercase string: %s\n", str);
return 0;
}
2.15 实例16：字符串反转
#include <stdio.h>
#include <string.h>
void reverse_string(char *str) {
int len = strlen(str);
for (int i = 0; i < len / 2; i++) {
char temp = str[i];
str[i] = str[len - i - 1];
str[len - i - 1] = temp;
}
}
int main() {
char str[] = "Hello, World!";
printf("Original string: %s\n", str);
reverse_string(str);
printf("Reversed string: %s\n", str);
return 0;
}
2.16 实例17：字符串替换
#include <stdio.h>
#include <string.h>
void string_replace(char *str, char *old_str, char *new_str) {
char result[100];
int len = strlen(str);
int j = 0;
for (int i = 0; i < len; i++) {
if (str[i] == old_str[0]) {
int k = 1;
while (str[i + k] == old_str[k]) {
k++;
}
if (k == strlen(old_str)) {
for (int p = 0; p < strlen(new_str); p++) {
result[j++] = new_str[p];
}
i += k - 1;
}
} else {
result[j++] = str[i];
}
}
result[j] = '\0';
strcpy(str, result);
}
int main() {
char str[] = "Hello, World!";
char old_str[] = "World";
char new_str[] = "Programming";
string_replace(str, old_str, new_str);
printf("Replaced string: %s\n", str);
return 0;
}
2.17 实例18：计算最大公约数
#include <stdio.h>
int gcd(int a, int b) {
if (b == 0)
return a;
return gcd(b, a % b);
}
int main() {
int a = 24;
int b = 18;
int result = gcd(a, b);
printf("GCD of %d and %d is %d\n", a, b, result);
return 0;
}
2.18 实例19：计算最小公倍数
#include <stdio.h>
int lcm(int a, int b) {
return (a / gcd(a, b)) * b;
}
int main() {
int a = 12;
int b = 18;
int result = lcm(a, b);
printf("LCM of %d and %d is %d\n", a, b, result);
return 0;
}
2.19 实例20：计算阶乘
#include <stdio.h>
int factorial(int n) {
if (n == 0)
return 1;
return n * factorial(n - 1);
}
int main() {
int n = 5;
printf("Factorial of %d is %d\n", n, factorial(n));
return 0;
}
2.20 实例21：判断素数
#include <stdio.h>
#include <stdbool.h>
bool is_prime(int n) {
if (n <= 1)
return false;
for (int i = 2; i * i <= n; i++) {
if (n % i == 0)
return false;
}
return true;
}
int main() {
int n = 17;
if (is_prime(n))
printf("%d is a prime number\n", n);
else
printf("%d is not a prime number\n", n);
return 0;
}
2.21 实例22：判断回文数
#include <stdio.h>
bool is_palindrome(int n) {
int reversed = 0, original = n, remainder;
while (n != 0) {
remainder = n % 10;
reversed = reversed * 10 + remainder;
n /= 10;
}
return original == reversed;
}
int main() {
int n = 121;
if (is_palindrome(n))
printf("%d is a palindrome\n", n);
else
printf("%d is not a palindrome\n", n);
return 0;
}
2.22 实例23：计算最大公约数
#include <stdio.h>
int gcd(int a, int b) {
if (b == 0)
return a;
return gcd(b, a % b);
}
int main() {
int a = 24;
int b = 18;
int result = gcd(a, b);
printf("GCD of %d and %d is %d\n", a, b, result);
return 0;
}
2.23 实例24：计算最小公倍数
#include <stdio.h>
int lcm(int a, int b) {
return (a / gcd(a, b)) * b;
}
int main() {
int a = 12;
int b = 18;
int result = lcm(a, b);
printf("LCM of %d and %d is %d\n", a, b, result);
return 0;
}
2.24 实例25：计算阶乘
#include <stdio.h>
int factorial(int n) {
if (n == 0)
return 1;
return n * factorial(n - 1);
}
int main() {
int n = 5;
printf("Factorial of %d is %d\n", n, factorial(n));
return 0;
}
2.25 实例26：判断素数
”`c
#include
bool is_prime(int n) {
if (n <= 1)
return false;
for (int i = 2; i * i <= n; i++) {
if (n % i == 0)
return false;
}
return true;
}
int main() {
int n = 17;
if (is_prime(n))
printf("%d is a prime number\n", n);
else
printf("%d