查找字符串在列表中首次出现的位置

def find_first_occurrence(lst, target):
    for i in range(len(lst)):
        if lst[i] == target:
            return i
    return -1  # 如果字符串不存在于列表中，返回-1

# 示例用法
my_list = ['apple', 'banana', 'orange', 'apple', 'grape']
target_string = 'apple'
result = find_first_occurrence(my_list, target_string)
if result != -1:
    print(f"The first occurrence of '{target_string}' is at index {result}.")
else:
    print(f"'{target_string}' is not found in the list.")