C语言将"1697159487000"转化成"1697159487"
时间: 2024-01-29 18:10:47 浏览: 24
C语言可以通过使用字符串处理函数将字符串转化为整数,然后再将整数转化为字符串来实现将"1697159487000"转化成"1697159487"的操作。下面是一个示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
char str[] = "1697159487000";
long long int num = atoll(str);
char result[11];
sprintf(result, "%lld", num);
printf("%s\n", result); // 输出:1697159487
return 0;
}
```
在上面的代码中,我们首先使用`atoll()`函数将字符串转化为长整型数值,然后使用`sprintf()`函数将长整型数值转化为字符串,并将结果存储在`result`数组中。最后,我们使用`printf()`函数将结果打印出来。
相关问题
用C语言将表达式转化成后缀表达式
Sure, I can help you with that! Basically, to convert an infix expression to postfix expression using C language, we can use the stack data structure. Here's the basic algorithm:
1. Create a stack and push a left parenthesis '(' onto it.
2. Scan the infix expression from left to right.
3. If the current token is an operand, append it to the postfix expression.
4. If the current token is a left parenthesis, push it onto the stack.
5. If the current token is a right parenthesis, pop operators from the stack and append them to the postfix expression until a left parenthesis is found. Discard the left parenthesis.
6. If the current token is an operator, pop operators from the stack and append them to the postfix expression until an operator with lower precedence or a left parenthesis is found. Push the current operator onto the stack.
7. After the infix expression is scanned, pop any remaining operators from the stack and append them to the postfix expression.
And here's an example C program that implements this algorithm:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_EXPR_LEN 100
#define MAX_STACK_SIZE 100
int is_operator(char c) {
return (c == '+' || c == '-' || c == '*' || c == '/');
}
int get_precedence(char c) {
switch (c) {
case '+':
case '-':
return 1;
case '*':
case '/':
return 2;
default:
return 0;
}
}
void infix_to_postfix(char *infix_expr, char *postfix_expr) {
int len = strlen(infix_expr);
char *stack = malloc(MAX_STACK_SIZE * sizeof(char));
int top = 0;
int i, j;
stack[top] = '(';
j = 0;
for (i = 0; i < len; i++) {
char c = infix_expr[i];
if (c == ' ') {
continue;
} else if (isdigit(c)) {
postfix_expr[j++] = c;
} else if (is_operator(c)) {
while (get_precedence(c) <= get_precedence(stack[top]) && stack[top] != '(') {
postfix_expr[j++] = stack[top--];
}
stack[++top] = c;
} else if (c == '(') {
stack[++top] = c;
} else if (c == ')') {
while (stack[top] != '(') {
postfix_expr[j++] = stack[top--];
}
top--;
}
}
while (top > 0) {
postfix_expr[j++] = stack[top--];
}
postfix_expr[j] = '\0';
free(stack);
}
int main() {
char infix_expr[MAX_EXPR_LEN];
printf("Please enter the infix expression: ");
fgets(infix_expr, MAX_EXPR_LEN, stdin);
infix_to_postfix(infix_expr, infix_expr);
printf("The postfix expression is: %s\n", infix_expr);
return 0;
}
And here's an example of how to use the program:
Please enter the infix expression: (1+2)*3-4/5
The postfix expression is: 12+3*45/-
c语言将字符数组转化成double
以下是将字符数组转换为double的C语言代码示例:
```c
#include <stdio.h>
#include <stdlib.h>
int main()
{
char str[] = "3.1415926";
char *ptr;
double num;
num = strtod(str, &ptr);
printf("The number is %lf\n", num);
return 0;
}
```
在上面的代码中,我们使用了`strtod()`函数将字符串转换为double类型的数字。该函数的第一个参数是要转换的字符串,第二个参数是指向字符指针的指针,用于存储第一个无法转换的字符的地址。如果字符串中的所有字符都可以转换为数字,则该指针将指向字符串的结尾。
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