我需要一種編輯字符串的方法

Question

給定一個像「/documents/filename.txt」這樣的字符串，我需要生成一個新的字符串「/documents/filename_out.txt」，其中新字符串只是將_out附加到文件名，同時保留.txt後綴。

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

int main(){; 
    char fileName[80]; 
    printf("Please enter filename: "); 
    scanf("%s", fileName); 
    char outName[]; 

    printf("Outputname: %s\n", outName); 
} 

有沒有一種辦法，也就是說，從一個字符串中刪除最後4個字符文件（.txt），然後追加與「_out.txt」的字符串？

在此先感謝！

Answer 1

使用函數strtok來標記輸入並再次連接它們，並在每個標記之間使用_out。

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

int main(){; 
char fileName[80]; 
printf("Please enter filename: "); 
scanf("%s", fileName); 
char outName[80]; 
char *name, *type; 

name = strtok(fileName, "."); 
type = strtok(NULL, "."); 

snprintf(outName, 80, "%s_out.%s", name, type); 
outName[79] ='\0'; 


printf("Outputname: %s\n", outName); 
} 

PS。我假設你的輸入總是正確的，所以它不檢查任何東西，除非確保outName將始終是一個正確的字符串，用NULL字符結束。

Answer 2

// strlen(".txt") = 4  
strcpy(filename + strlen(filename) - 4, "_out.txt"); 

您需要確保緩衝區足夠大以容納額外的4個字符。

Answer 3

下面是您的問題的一個相當具體的解決方案。

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

int main(){ 

    char newSuffix[] = "_out.txt"; 

    char fileName[80]; 
    printf("Please enter filename: "); 
    scanf("%s", fileName); 
    char outName[85]; 

    strcpy(outName, fileName); 
    strcpy(&outName[strlen(fileName) - 4], newSuffix); 

    printf("Outputname: %s\n", outName); 
} 

Answer 4

Google是你的朋友。這是搜索查詢的第一個命中：「c替代字符串」。你需要什麼權利在這裏：What is the function to replace string in C?

#include <stdlib.h> 
#include <stdio.h> 
#include <string.h> 
int main(){ 
    char fileName[80]; 
    printf("Please enter filename: "); 
    scanf("%s", fileName); 
    char outName[]; 
    printf("Outputname: %s\n", replace(filename,".txt","_out.txt")); 
} 


char * replace(
    char const * const original, 
    char const * const pattern, 
    char const * const replacement 
) { 
    size_t const replen = strlen(replacement); 
    size_t const patlen = strlen(pattern); 
    size_t const orilen = strlen(original); 

    size_t patcnt = 0; 
    const char * oriptr; 
    const char * patloc; 

    // find how many times the pattern occurs in the original string 
    for (oriptr = original; patloc = strstr(oriptr, pattern); oriptr = patloc + patlen) 
    { 
    patcnt++; 
    } 

    { 
    // allocate memory for the new string 
    size_t const retlen = orilen + patcnt * (replen - patlen); 
    char * const returned = (char *) malloc(sizeof(char) * (retlen + 1)); 

    if (returned != NULL) 
    { 
     // copy the original string, 
     // replacing all the instances of the pattern 
     char * retptr = returned; 
     for (oriptr = original; patloc = strstr(oriptr, pattern); oriptr = patloc + patlen) 
     { 
     size_t const skplen = patloc - oriptr; 
     // copy the section until the occurence of the pattern 
     strncpy(retptr, oriptr, skplen); 
     retptr += skplen; 
     // copy the replacement 
     strncpy(retptr, replacement, replen); 
     retptr += replen; 
     } 
     // copy the rest of the string. 
     strcpy(retptr, oriptr); 
    } 
    return returned; 
    } 
} 

Answer 5

char outName[sizeof(fileName)+4]; 
strcpy(outName, fileName); 
strcpy(strstr(outName, ".txt"), "_out.txt"); 
//strcpy(strrchr(outName, '.'), "_out.txt");