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字符串与数字之间的转换

2024-07-11 13:24:43   222人阅读

1. itoa

itoa是广泛应用的非标准c语言扩展函数，头文件为 #icnlude<stdlib.h>

char* itoa(int value,char* string,int radix);

#include<iostream>#include<cstdlib>using namespace std;int main(){	int i=15;	char str[25];	itoa(i,str,16);	cout<<str<<endl;	return 0;}

 

2. sprintf

C的库函数，头文件#include<stdlib.h>

int sprintf( char *buffer, const char *format, [ argument] … );

#include<stdio.h>#include<stdlib.h>int main(){	char buffer[50];	int n,a=5,b=3;	n = sprintf(buffer,"%dplus%dis%d",a,b,a+b);	printf("[ %s ] is a string %d chars long\n",buffer,n);/*“格式输出”*/	 	return 0;}

 

3.atoi

C库函数，#icnlude<stdlib.h>

int atoi(const char *nptr);

#include<stdlib.h>#include<stdio.h>int main(void){	double n;	char*str="12345.67";	n=atoi(str);	printf("string=%s integer=%d\n",str,(int)n);	return 0;}

4. atoi的一个实现

#include <iostream>using namespace std;void main(void){	char str[20];      	int i,n=0;		cout<<"Enter the string:";         	cin.getline(str,20,‘\n‘);	    for (i=0; str[i] != ‘\0‘; i++) 		n = n*10+(str[i]-‘0‘);	cout<<"Corresponding number is "<<n<<endl;    cout<<"The digits of the number from low to high is ";	while(n){		cout<<n%10<<‘,‘;   		n/=10;	}	cout<<endl;}

　　


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