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掌握C语言，轻松破解编程难题：50个实战案例深度解析

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1. C语言基础入门

C语言作为一种历史悠久的编程语言，以其高效、灵活和强大的功能而闻名。要想掌握C语言，首先需要了解其基础语法和常用数据类型。

1.1 基础语法

  • 变量定义：int a;
  • 常量定义：const int PI = 3.14159;
  • 运算符：+, -, *, /, %, ==, !=, >, <, >=, <=
  • 控制语句：if, else, switch, for, while, do...while
  • 函数：int sum(int a, int b) { return a + b; }

1.2 常用数据类型

  • 整型：int, short, long, char
  • 浮点型：float, double
  • 字符串：char[] 或 char*

2. 实战案例解析

以下列举了50个实战案例，帮助读者深入理解C语言编程。

2.1 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;
    printf("Enter a number: ");
    scanf("%d", &n);
    printf("Factorial of %d is %d\n", n, factorial(n));
    return 0;
}

2.2 求最大公约数

#include <stdio.h>

int gcd(int a, int b) {
    if (b == 0) {
        return a;
    }
    return gcd(b, a % b);
}

int main() {
    int x, y;
    printf("Enter two numbers: ");
    scanf("%d %d", &x, &y);
    printf("GCD of %d and %d is %d\n", x, y, gcd(x, y));
    return 0;
}

2.3 检查素数

#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;
    printf("Enter a number: ");
    scanf("%d", &n);
    if (is_prime(n)) {
        printf("%d is a prime number\n", n);
    } else {
        printf("%d is not a prime number\n", n);
    }
    return 0;
}

2.4 水仙花数

#include <stdio.h>

int is_narcissistic(int n) {
    int sum = 0, temp = n;
    while (temp) {
        int digit = temp % 10;
        sum += digit * digit * digit;
        temp /= 10;
    }
    return sum == n;
}

int main() {
    int n;
    printf("Enter a number: ");
    scanf("%d", &n);
    if (is_narcissistic(n)) {
        printf("%d is a narcissistic number\n", n);
    } else {
        printf("%d is not a narcissistic number\n", n);
    }
    return 0;
}

2.5 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[100];
    printf("Enter a string: ");
    scanf("%s", str);
    reverse_string(str);
    printf("Reversed string: %s\n", str);
    return 0;
}

2.6 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;
}

2.7 查找数组中的最大值

#include <stdio.h>

int find_max(int arr[], int n) {
    int max = arr[0];
    for (int i = 1; i < n; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    return max;
}

int main() {
    int arr[] = {64, 34, 25, 12, 22, 11, 90};
    int n = sizeof(arr) / sizeof(arr[0]);
    printf("Maximum element in the array is %d\n", find_max(arr, n));
    return 0;
}

2.8 判断闰年

#include <stdio.h>

int is_leap_year(int year) {
    if (year % 4 == 0) {
        if (year % 100 != 0) {
            return 1;
        } else {
            if (year % 400 == 0) {
                return 1;
            }
        }
    }
    return 0;
}

int main() {
    int year;
    printf("Enter a year: ");
    scanf("%d", &year);
    if (is_leap_year(year)) {
        printf("%d is a leap year\n", year);
    } else {
        printf("%d is not a leap year\n", year);
    }
    return 0;
}

2.9 计算斐波那契数列

#include <stdio.h>

int fibonacci(int n) {
    if (n <= 1) {
        return n;
    }
    return fibonacci(n - 1) + fibonacci(n - 2);
}

int main() {
    int n;
    printf("Enter a number: ");
    scanf("%d", &n);
    printf("Fibonacci of %d is %d\n", n, fibonacci(n));
    return 0;
}

2.10 寻找数组中的最小值

#include <stdio.h>

int find_min(int arr[], int n) {
    int min = arr[0];
    for (int i = 1; i < n; i++) {
        if (arr[i] < min) {
            min = arr[i];
        }
    }
    return min;
}

int main() {
    int arr[] = {64, 34, 25, 12, 22, 11, 90};
    int n = sizeof(arr) / sizeof(arr[0]);
    printf("Minimum element in the array is %d\n", find_min(arr, n));
    return 0;
}

2.11 判断回文数

#include <stdio.h>
#include <stdbool.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;
    printf("Enter a number: ");
    scanf("%d", &n);
    if (is_palindrome(n)) {
        printf("%d is a palindrome\n", n);
    } else {
        printf("%d is not a palindrome\n", n);
    }
    return 0;
}

2.12 判断素数（另一种方法）

#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;
    printf("Enter a number: ");
    scanf("%d", &n);
    if (is_prime(n)) {
        printf("%d is a prime number\n", n);
    } else {
        printf("%d is not a prime number\n", n);
    }
    return 0;
}

2.13 字符串查找

#include <stdio.h>
#include <string.h>

int find_substring(char *str, char *substr) {
    int index = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        if (str[i] == substr[0]) {
            for (int j = 0; j < strlen(substr); j++) {
                if (str[i + j] != substr[j]) {
                    break;
                }
                if (j == strlen(substr) - 1) {
                    index = i;
                    return index;
                }
            }
        }
    }
    return -1;
}

int main() {
    char str[100], substr[100];
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Enter a substring: ");
    scanf("%s", substr);
    int index = find_substring(str, substr);
    if (index != -1) {
        printf("Substring found at index %d\n", index);
    } else {
        printf("Substring not found\n");
    }
    return 0;
}

2.14 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[100];
    printf("Enter a string: ");
    scanf("%s", str);
    reverse_string(str);
    printf("Reversed string: %s\n", str);
    return 0;
}

2.15 合并两个有序数组

#include <stdio.h>

void merge_arrays(int arr1[], int n1, int arr2[], int n2, int merged[]) {
    int i = 0, j = 0, k = 0;
    while (i < n1 && j < n2) {
        if (arr1[i] < arr2[j]) {
            merged[k++] = arr1[i++];
        } else {
            merged[k++] = arr2[j++];
        }
    }
    while (i < n1) {
        merged[k++] = arr1[i++];
    }
    while (j < n2) {
        merged[k++] = arr2[j++];
    }
}

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]);
    int merged[n1 + n2];
    merge_arrays(arr1, n1, arr2, n2, merged);
    printf("Merged array: ");
    for (int i = 0; i < n1 + n2; i++) {
        printf("%d ", merged[i]);
    }
    printf("\n");
    return 0;
}

2.16 字符串排序

#include <stdio.h>
#include <string.h>

void sort_string(char *str) {
    int len = strlen(str);
    for (int i = 0; i < len - 1; i++) {
        for (int j = i + 1; j < len; j++) {
            if (str[i] > str[j]) {
                char temp = str[i];
                str[i] = str[j];
                str[j] = temp;
            }
        }
    }
}

int main() {
    char str[100];
    printf("Enter a string: ");
    scanf("%s", str);
    sort_string(str);
    printf("Sorted string: %s\n", str);
    return 0;
}

2.17 计算字符串长度

#include <stdio.h>
#include <string.h>

int string_length(char *str) {
    int len = 0;
    while (str[len] != '\0') {
        len++;
    }
    return len;
}

int main() {
    char str[100];
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Length of string: %d\n", string_length(str));
    return 0;
}

2.18 字符串查找（另一种方法）

#include <stdio.h>
#include <string.h>

int find_substring(char *str, char *substr) {
    int index = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        if (str[i] == substr[0]) {
            int j = 0;
            while (substr[j] != '\0') {
                if (str[i + j] != substr[j]) {
                    break;
                }
                j++;
            }
            if (substr[j] == '\0') {
                index = i;
                return index;
            }
        }
    }
    return -1;
}

int main() {
    char str[100], substr[100];
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Enter a substring: ");
    scanf("%s", substr);
    int index = find_substring(str, substr);
    if (index != -1) {
        printf("Substring found at index %d\n", index);
    } else {
        printf("Substring not found\n");
    }
    return 0;
}

2.19 字符串替换

#include <stdio.h>
#include <string.h>

void replace_string(char *str, char *old, char *new) {
    char buffer[1000];
    char *temp = str;
    while ((temp = strstr(temp, old)) != NULL) {
        strncpy(buffer, str, temp - str);
        buffer[temp - str] = '\0';
        strcat(buffer, new);
        strcat(buffer, temp + strlen(old));
        strcpy(str, buffer);
        temp = buffer;
    }
}

int main() {
    char str[100], old[100], new[100];
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Enter the substring to be replaced: ");
    scanf("%s", old);
    printf("Enter the new substring: ");
    scanf("%s", new);
    replace_string(str, old, new);
    printf("Replaced string: %s\n", str);
    return 0;
}

2.20 判断是否为回文字符串

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

bool is_palindrome(char *str) {
    int len = strlen(str);
    for (int i = 0; i < len / 2; i++) {
        if (str[i] != str[len - i - 1]) {
            return false;
        }
    }
    return true;
}

int main() {
    char str[100];
    printf("Enter a string: ");
    scanf("%s", str);
    if (is_palindrome(str)) {
        printf("The string is a palindrome\n");
    } else {
        printf("The string is not a palindrome\n");
    }
    return 0;
}

2.21 查找字符串中字符的出现次数

#include <stdio.h>
#include <string.h>

int count_chars(char *str, char ch) {
    int count = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        if (str[i] == ch) {
            count++;
        }
    }
    return count;
}

int main() {
    char str[100], ch;
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Enter a character to count: ");
    scanf(" %c", &ch);
    printf("The character '%c' appears %d times in the string\n", ch, count_chars(str, ch));
    return 0;
}

2.22 查找字符串中子字符串的出现次数

#include <stdio.h>
#include <string.h>

int count_substring(char *str, char *substr) {
    int count = 0;
    int index = 0;
    while ((index = strstr(str, substr)) != NULL) {
        count++;
        str = index + strlen(substr);
    }
    return count;
}

int main() {
    char str[100], substr[100];
    printf("Enter a string: ");
    scanf("%s", str);
    printf("Enter a substring to count: ");
    scanf("%s", substr);
    printf("The substring '%s' appears %d times in the string\n", substr, count_substring(str, substr));
    return 0;
}

2.23 删除字符串中的重复字符

”`c #include #include #include

void remove_duplicate_chars(char *str) {

int len = strlen(str);
for (int i = 0; i < len - 1; i++) {
    for (int j = i + 1; j < len; j++) {
        if (str[i] == str[j]) {
            str[j] = str[j + 1];
            len--;
            j--;
        }
    }
}
str
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