C语言 在 C 中将 Char * 转换为大写
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Converting Char * to Uppercase in C
提问by EDEDE
I'm trying to convert a char *to uppercase in c, but the function toupper()doesn't work here.
我正在尝试将char *c 中的 a转换为大写，但该函数toupper()在这里不起作用。
I'm trying to get the name of the the value of temp, the name being anything before the colon, in this case it's "Test", and then I want to capitalize the name fully.
我正在尝试获取 temp 值的名称，名称是冒号之前的任何名称，在本例中为“Test”，然后我想将名称完全大写。
void func(char * temp) {
// where temp is a char * containing the string "Test:Case1"
char * name;
name = strtok(temp,":");
//convert it to uppercase
name = toupper(name); //error here
}
I'm getting the error that the function toupper expects an int, but receives a char *. Thing is, I have to use char *'s, since that is what the function is taking in, (I can't really use char arrays here, can I?).
我收到错误，函数 toupper 需要一个 int，但收到一个 char *。问题是，我必须使用 char *'s，因为这是函数所接受的，（我不能在这里真正使用 char 数组，是吗？）。
Any help would be greatly appreciated.
任何帮助将不胜感激。
回答by chux - Reinstate Monica
toupper()converts a single char.
toupper()转换单个char.
Simply use a loop:
只需使用循环：
void func(char * temp) {
char * name;
name = strtok(temp,":");
// Convert to upper case
char *s = name;
while (*s) {
*s = toupper((unsigned char) *s);
s++;
}
}
Detail: The standard Library function toupper(int)is defined for all unsigned charand EOF. Since charmay be signed, convert to unsigned char.
详细信息：标准库函数toupper(int)是为所有unsigned char和定义的EOF。由于char可能已签名，因此转换为unsigned char.
Some OS's support a function call that does this: upstr()and strupr()
回答by wallyk
toupper()works only on a single character. But there is strupr()which is what you want for a pointer to a string.
toupper()仅适用于单个字符。但是strupr()对于指向字符串的指针，您需要的是什么。
回答by Sourav Ghosh
toupper()works on one element (intargument, value ranging the same as of unsigned charor EOF) at a time.
toupper()一次处理一个元素（int参数，值范围与 ofunsigned char或 EOF相同）。
Prototype:
原型：
int toupper(int c);
int toupper(int c);
You need to use a loop to supply one element at a time from your string.
您需要使用循环从string一次提供一个元素。
回答by Mike
For those of you who want to uppercase a string and store itin a variable (that was what I was looking for when I read these answers).
对于那些想要大写字符串并将其存储在变量中的人（这就是我阅读这些答案时所寻找的）。
#include <stdio.h> //<-- You need this to use printf.
#include <string.h> //<-- You need this to use string and strlen() function.
#include <ctype.h> //<-- You need this to use toupper() function.
int main(void)
{
string s = "I want to cast this"; //<-- Or you can ask to the user for a string.
unsigned long int s_len = strlen(s); //<-- getting the length of 's'.
//Defining an array of the same length as 's' to, temporarily, store the case change.
char s_up[s_len];
// Iterate over the source string (i.e. s) and cast the case changing.
for (int a = 0; a < s_len; a++)
{
// Storing the change: Use the temp array while casting to uppercase.
s_up[a] = toupper(s[a]);
}
// Assign the new array to your first variable name if you want to use the same as at the beginning
s = s_up;
printf("%s \n", s_up); //<-- If you want to see the change made.
}
Note:If you want to lowercase a string instead, change toupper(s[a])to tolower(s[a]).
注意：如果要改为小写字符串，请更改toupper(s[a])为tolower(s[a]).
