一、文件中常用的函数

fopen()

打开文件

fopen(const char*  filename, const char* mode)

filename：文件名
mode：打开方式，控制读写权限，数据形式为字符串，一般为:

r	只读
w	只写
r+	读写
w+	更新，写入
a	保留之前的内容写入

fputs()

向输入流stream写入数据

fputs(const char*  str, FILE *stream)

str: 存储数据的字符数组

fflush()

刷新缓冲区，即将缓冲区的数据立刻写入文件，同时清空缓冲区。

fflush(FILE *stream)

fclose()

关闭一个文件流，释放指针和有关的缓冲区。

fflush(FILE *stream)

二、使用实例

文件名为config.txt，内容如下

name:张三
sex:男
age:60
income:8000

1.读取文件

代码如下：

int GetConfigFromFile(char *filename)
{FILE *f = fopen(filename, "r");char buffer[1024];char *b;char *p;char *stop;char *last;if(NULL == f){printf("Failed to open %s\n", filename);return 0;}printf("Open file %s successfully\n", filename);while(NULL != (b = fgets(buffer, 1024, f))){if(b[0] == '#') continue;p = strtok_r(b, ":", &last);if(p != NULL){char* val = strtok_r(last, "\n", &last);if(NULL ==val)continue;else{while((*val == ' ')||(*val == '\t')){val++;}if(strstr(p, "name")) strncpy(m_name, val, sizeof(m_name) - 1);else if(strstr(p, "sex")) strncpy(m_sex, val, sizeof(m_sex) - 1);else if(strstr(p, "age"))m_age = strtol(val, &stop, 0); else if(strstr(p, "income")) m_income = strtol(val, &stop, 0);elseprintf("Unknown message: %s\n", p);}}}fclose(f);return 1;
}

运行结果如下：
在这里插入图片描述

2.写入文件

代码如下：

int WriteConfigFromFile(char *filename)
{FILE *f = fopen(filename, "w+");if(NULL == f){printf("file is not exist\n");return 0;}printf("Open file successfully\n");char buffer[1024] = {0};snprintf(buffer, 1024, "name:%s\n", m_name);fputs(buffer, f);memset(buffer, 0, 1024);snprintf(buffer, 1024, "age:%d\n", m_age);fputs(buffer, f);memset(buffer, 0, 1024);snprintf(buffer, 1024, "sex:%s\n", m_sex);fputs(buffer, f);memset(buffer, 0, 1024);snprintf(buffer, 1024, "income:%d\n", m_income);fputs(buffer, f);fflush(f);fclose(f);return 1;
}

运行结果如下：在这里插入图片描述

3.main()

int main()
{char filename[32] = {0};strncpy(filename, "config.txt", 32);if(0==GetConfigFromFile(filename)){printf("Read file faily\n");return 0;}else{printf("Read file successfully\n");printf("my name is %s, age is %d, sex is %s, income is %d\n", m_name, m_age, m_sex, m_income);}strncpy(m_name, "李四", sizeof(m_name) - 1);strncpy(m_sex, "女", sizeof(m_sex) - 1);m_age = 59;m_income = 20;if(0 == WriteConfigFromFile(filename)){printf("Write file faily\n");return 0;}printf("Write file successfully\n");return 0;
}